Trouble starting

[OverlandMan]

Since my big fuel system rebuild, the car runs much better and things are looking up; however, I've now got a starting issue I didn't have prior to the rebuild. In order to get the car started right now (regardless of hot or cold), I have to push down on the air plate a decent ways down in order to "prime" the injectors before starting. It's a delicate process because you can flood it out real easily doing this. Currently this is the only way I can get the car running.

Now I did replace my fuel accumulator back maybe 18 months ago? to fix a hot start issue. Could this be the culprit again and already?

The cold start valve seems to work because with the thermotime switch "cold" the engine will start and then stop almost immediately. Sometimes if I crank long enough I can get it to sputter a bit and every now and then I might even be able to get it running albeit a crappy process.

Any ideas? Like I said, once it's running it runs well.

[David T]

Since my big fuel system rebuild, the car runs much better and things are looking up; however, I've now got a starting issue I didn't have prior to the rebuild. In order to get the car started right now (regardless of hot or cold), I have to push down on the air plate a decent ways down in order to "prime" the injectors before starting. It's a delicate process because you can flood it out real easily doing this. Currently this is the only way I can get the car running.

Now I did replace my fuel accumulator back maybe 18 months ago? to fix a hot start issue. Could this be the culprit again and already?

The cold start valve seems to work because with the thermotime switch "cold" the engine will start and then stop almost immediately. Sometimes if I crank long enough I can get it to sputter a bit and every now and then I might even be able to get it running albeit a crappy process.

Any ideas? Like I said, once it's running it runs well.

Get a dwell meter on the Lambda system and check the duty cycle. I am guessing the mixture is not right. Also check for vacuum leaks.

[Jonathan]

Any chance you reversed the flexible rubber fuel lines up at the pump? Like the pressure side of the pump going into the hardline for the return and vice versa?

[OverlandMan]

Get a dwell meter on the Lambda system and check the duty cycle. I am guessing the mixture is not right. Also check for vacuum leaks.

If it was a mixture or vacuum problem wouldn't that make it run crappy too? It doesn't run crappy....



Any chance you reversed the flexible rubber fuel lines up at the pump? Like the pressure side of the pump going into the hardline for the return and vice versa?


I suppose anything is possible. I can double-check tonight... but would the car run in this configuration?

[Jonathan]

I suppose anything is possible. I can double-check tonight... but would the car run in this configuration?

Likely not run, crappy or otherwise. I wasn't sure if your summary meant you can either struggle to get it to start (at all), or force it to start (pushing the plate down) and then it dies (i.e. won't stay running).

Once you get it started with the plate pushdown routine, does it stay running?

I've never experimented enough with the fuel system to know what theoretically is possible or isn't, but considering much of it is in a loop from the pump and back, if it got pumped down the return line and then the plate forced fuel into the engine manually, then maybe it could start or run briefly routed backwards.

[OverlandMan]

Likely not run, crappy or otherwise. I wasn't sure if your summary meant you can either struggle to get it to start (at all), or force it to start (pushing the plate down) and then it dies (i.e. won't stay running).

Once you get it started with the plate pushdown routine, does it stay running?

I've never experimented enough with the fuel system to know what theoretically is possible or isn't, but considering much of it is in a loop from the pump and back, if it got pumped down the return line and then the plate forced fuel into the engine manually, then maybe it could start or run briefly routed backwards.

What's happening is I can't get it to start without pushing down on the air plate and running the fuel pump for a few seconds before starting. This is what I meant by "priming". Sometimes I'll wedge a paint stick in there to keep the air plate down and then rotate the ignition key a couple of times to run the pump (but not actually start yet). I can also jump the RPM relay for a few seconds to accomplish the same thing. Then I stop pushing on the air plate and start the engine. It's not smooth and sometimes it will flood but this seems to be the only way I can get it started. Once the car is started, it runs great.

If I don't go through all that and just try to start the car normally (without touching anything in the engine compartment) one of three things happens. First, with the thermotime switch cold, the CSV will fire the engine for a few seconds and then die. Second, the car tries to sputter and catch during starting but usually never successfully. Third, the starter just cranks and cranks with no indication of trying to run. Usually at this point I stop and let it sit for a few minutes. Then I'll try it again and the process repeats.

[Jonathan]

What comes to mind is something along the lines of your fuel pump or fuel feed side plumbing needs to overcome some resistance or obstacle and then once it does, it's good to go.

Makes me think of a pump (in any circumstance, but in this case your fuel pump) that is starving on the suction side. Which fuel pump do you have? The original or the sender/pump combo unit?

If forcing it to stay on and prime draws fuel up the pick-up hose in the tank to the suction port on the pump fixes it, maybe that's where the problem is centred? Like something wrong with the "tuna can" sort of pick-up filter or some other arrangement depending on what you have in your car.

If you force it on with the CSV or another pathway, it still won't have new fuel in the lines until the pump catches up and primes but it could be roughly running the engine with the fuel still in the lines and then finally sort itself out.

If it is a suction side problem, the kind where it is okay as long as the pump stays on, maybe that is saying that when you shut it off, the fuel slowly drips back down into the tank and now the suction side of the pump is empty.

It's the kind of thing you might see with a sump pump in your basement or at the cottage. If the check valve on the suction side isn't holding properly, the water that would normally stay in the suction piping falls back down and it can have trouble getting started again.

Just another idea anyway. Trying to add up what you see and what you don't. Still makes me think it is something around an issue that needs overcoming and then once it is, the car is fine. It narrows down your search at least anyway.

[OverlandMan]

What comes to mind is something along the lines of your fuel pump or fuel feed side plumbing needs to overcome some resistance or obstacle and then once it does, it's good to go.

Makes me think of a pump (in any circumstance, but in this case your fuel pump) that is starving on the suction side. Which fuel pump do you have? The original or the sender/pump combo unit?

If forcing it to stay on and prime draws fuel up the pick-up hose in the tank to the suction port on the pump fixes it, maybe that's where the problem is centred? Like something wrong with the "tuna can" sort of pick-up filter or some other arrangement depending on what you have in your car.

If you force it on with the CSV or another pathway, it still won't have new fuel in the lines until the pump catches up and primes but it could be roughly running the engine with the fuel still in the lines and then finally sort itself out.

If it is a suction side problem, the kind where it is okay as long as the pump stays on, maybe that is saying that when you shut it off, the fuel slowly drips back down into the tank and now the suction side of the pump is empty.

It's the kind of thing you might see with a sump pump in your basement or at the cottage. If the check valve on the suction side isn't holding properly, the water that would normally stay in the suction piping falls back down and it can have trouble getting started again.

Just another idea anyway. Trying to add up what you see and what you don't. Still makes me think it is something around an issue that needs overcoming and then once it is, the car is fine. It narrows down your search at least anyway.

I think I follow your logic. The pump and all tank components have been replaced. I'm running the OEM style setup, not the new version. If the pump were starving, I would think it wouldn't run at all. Isn't that why the accumulator is in between the pump and the filter/fuel dist, to hold rest pressure? I replaced the accumulator, though it's been a year and a half. I wouldn't think it would have crapped out already but maybe?

I'm just trying to narrow it down and perform any tests I can to do so before I just start throwing money at it. On the plus side, I've replaced darned near everything on the fuel system.

[Bitsyncmaster]

Since you can get it started, I would check the mixture setting with the dwell. Your car can run with the mixture off but it can cause hard starting when the mixture is off.

[OverlandMan]

Since you can get it started, I would check the mixture setting with the dwell. Your car can run with the mixture off but it can cause hard starting when the mixture is off.

Can you send me a link to this procedure? I've seen it referenced on here several times before but don't fully understand the dwell concept.

Thanks

[Jonathan]

Can you send me a link to this procedure? I've seen it referenced on here several times before but don't fully understand the dwell concept.

Thanks

I'd imagine Dave's suggestion is a very good one... and my experience with it is exactly like you said yours is. :) For good or for bad, I've not done any dwell stuff on my car, so I'll bow out for the moment and let you see how it goes (let us know what comes of it though).

[Bitsyncmaster]

Can you send me a link to this procedure? I've seen it referenced on here several times before but don't fully understand the dwell concept.

Thanks

Your just adjusting the duty cycle of the frequency valve to a value where the car was designed to run best. Dwell is a meter that reads duty cycle but on a different scale. They specified using the 4 cylinder dwell to get the most accurate readings and most auto repair shops had dwell meters already.

So you attach the red wire on the dwell meter to the orange wire that is in a two pin connector on the harness behind the engine. That wire also goes to the diagnostic connector but I removed mine. You can also read the dwell from one of the wires driving the frequency valve.

Black wire on the dwell meter goes to ground (engine metal screw or bracket works).

Book value to set is the average of the reading at 40 degrees. You read that value on a warmed up engine at idle speed.

[OverlandMan]

Your just adjusting the duty cycle of the frequency valve to a value where the car was designed to run best. Dwell is a meter that reads duty cycle but on a different scale. They specified using the 4 cylinder dwell to get the most accurate readings and most auto repair shops had dwell meters already.

So you attach the red wire on the dwell meter to the orange wire that is in a two pin connector on the harness behind the engine. That wire also goes to the diagnostic connector but I removed mine. You can also read the dwell from one of the wires driving the frequency valve.

Black wire on the dwell meter goes to ground (engine metal screw or bracket works).

Book value to set is the average of the reading at 40 degrees. You read that value on a warmed up engine at idle speed.

Will a decent multimeter function as a dwell meter or do I need a specific tool/meter? Does this sound indicative of an engine starting but not running issue to you, Dave?

[Bitsyncmaster]

Will a decent multimeter function as a dwell meter or do I need a specific tool/meter? Does this sound indicative of an engine starting but not running issue to you, Dave?

I have a multimeter that will read the duty cycle. I don't use it because I have a Snap-ON dwell meter that also has a scale for duty cycle.

The mixture setting does interact with starting, cold running and wide open throttle. Our engine can start via the cold start valve and not run if the mixture is to far off.

The control pressure regulator (CPR, also called WUR) takes the place of a choke used on a carburetor. It runs our cold engines at an AFR or 10 to 12 until the engine has warmed up enough to go closed loop via the lambda system.

[OverlandMan]

Dave,

This is the multimeter I have. I'm not sure if it will accomplish this or not.
34827

[Bitsyncmaster]

Dave,

This is the multimeter I have. I'm not sure if it will accomplish this or not.
34827

Looks like that may work. Set Hz on the dial and press the Hz/Duty button. Duty numbers, you set 10% higher than the book values. So normal dwell average of 40 deg. would be 44 % Duty.

[OverlandMan]

Looks like that may work. Set Hz on the dial and press the Hz/Duty button. Duty numbers, you set 10% higher than the book values. So normal dwell average of 40 deg. would be 44 % Duty.

OK thanks. Will try this weekend and see what I can come up with. Where are the mixture settings? Those two offset screws in front of the air-plate?

[Jonathan]

Hey Jeff,

I found these online:


https://www.youtube.com/watch?v=cpNB1eRktzM

And:

https://www.youtube.com/watch?v=1fr0z1NqHX8

I don't have my own experience, but these clips show it pretty well. Mark's video points to the adjustment screw location, which doesn't really show the screw or an adjustment, but it's the one that's normally capped off to avoid the vacuum leak. Small adjustments at a time I think is the way to go.

[OverlandMan]

Well this was a frustrating weekend in terms of working on the DeLorean. Saturday I couldn't for the life of me get the car running. It could have been that I wasn't giving it the right touch/combination with the air-plate priming technique and all that. Regardless, the best I could do was get it to stumble a bit. Occasionally it would start and run for a second or two and then immediately die. Not wanting to burn-up the starter I gave up and didn't mess with it for the rest of the weekend.

Any thoughts are welcomed.

[Bitsyncmaster]

Best way to find starting problems is to do a fuel pressure check. But without a gauge, I would check your primary pressure control O-ring for damage. I have see that O-ring cause sudden lost of starting ability.

[OverlandMan]

Best way to find starting problems is to do a fuel pressure check. But without a gauge, I would check your primary pressure control O-ring for damage. I have see that O-ring cause sudden lost of starting ability.

Dave,

Where is this O-Ring? And should I invest in a gauge to check fuel pressure?

[David T]

Dave,

Where is this O-Ring? And should I invest in a gauge to check fuel pressure?

Not yet. Pull a plug and check for spark. Try a squirt of Ether. Check that the frequency valve is buzzing. Check the connections on the ballast resistor. If they are rusty clean them up. Make sure the fuel pump is running. If you haven't touched the Primary Pressure Regulator the "O" ring should be OK.

[OverlandMan]

Not yet. Pull a plug and check for spark. Try a squirt of Ether. Check that the frequency valve is buzzing. Check the connections on the ballast resistor. If they are rusty clean them up. Make sure the fuel pump is running. If you haven't touched the Primary Pressure Regulator the "O" ring should be OK.

I have spark. All plugs, wires, dist cap & rotor were replaced last year. The car was running great last weekend. The problem since my fuel system rebuild has been starting the car and nothing else so far. The ballast resistor connections have all been checked and the fuel pump was replaced earlier this year and works fine. The only thing I'm not sure about it the frequency valve buzzing.

Is Primary Pressure Regular and Control Pressure Regulator synonymous?

[Bitsyncmaster]

Is Primary Pressure Regular and Control Pressure Regulator synonymous?

PPR sets the fuel pump pressure at 75 PSI. The fuel pump is capable of pressures higher than 75 PSI so the PPR keeps pressures constant in the fuel system. PPR is located on right front side of fuel distributor under that large nut.

Control Pressure Regulator modifies the pressures to make the engine mixture rich during a cold engine.

If you plan to do K-jet trouble shooting, I highly recommend you get a K-jet fuel pressure gauge. Checking fuel pressure is the first thing you do when you don't know what's causing engine running problems.

[OverlandMan]

PPR sets the fuel pump pressure at 75 PSI. The fuel pump is capable of pressures higher than 75 PSI so the PPR keeps pressures constant in the fuel system. PPR is located on right front side of fuel distributor under that large nut.

Control Pressure Regulator modifies the pressures to make the engine mixture rich during a cold engine.

If you plan to do K-jet trouble shooting, I highly recommend you get a K-jet fuel pressure gauge. Checking fuel pressure is the first thing you do when you don't know what's causing engine running problems.

Ah I see. Is the PPR part of the fuel distributor housing?

What do you recommend for a gauge? Google K-Jet fuel pressure gauge?

[AugustneverEnds]

34894

Hope this helps out

[Bitsyncmaster]

Ah I see. Is the PPR part of the fuel distributor housing?

What do you recommend for a gauge? Google K-Jet fuel pressure gauge?

Here is one but if you shop around you can probably find one cheaper. Get one with the shut off valve like this one so you can check both primary pressure and control pressure with one setup.

http://www.amazon.com/Tool-Aid-33865-K-Jetronic-Injection/dp/B0002SR5NU

[OverlandMan]

34894

Hope this helps out

What's the DMCH part # for this? I'm not real clear on where this is.

[OverlandMan]

I'm still struggling to get this sorted. I couldn't get the car started at all last weekend. I plan on trying again this weekend. Thus I haven't been able to test the dwell yet. In thinking through this more, I do have a question.

What would be the symptoms or a failing/faulty WUR?

[DMCMW Dave]

I'm still struggling to get this sorted. I couldn't get the car started at all last weekend. I plan on trying again this weekend. Thus I haven't been able to test the dwell yet. In thinking through this more, I do have a question.

What would be the symptoms or a failing/faulty WUR?

High static fuel pressure read with a K-Jet gauge.

Hard Starting Cold (starts and dies)

No power at all until warmed up, acts like a carb with no accelerator pump.

[OverlandMan]

High static fuel pressure read with a K-Jet gauge.

Hard Starting Cold (starts and dies)

No power at all until warmed up, acts like a carb with no accelerator pump.

Thanks for the reply Dave. I've been debating calling you about this. Before I throw money at various parts, I'd like to narrow it down as much as possible. What about the frequency valve? What would the symptoms of a malfunction there be? Any other ideas? Thanks for all your help as always.

[David T]

Thanks for the reply Dave. I've been debating calling you about this. Before I throw money at various parts, I'd like to narrow it down as much as possible. What about the frequency valve? What would the symptoms of a malfunction there be? Any other ideas? Thanks for all your help as always.

The frequency valve has a low rate of failure. If it isn't buzzing it is usually a wiring or adjustment problem. If the valve isn't buzzing the motor would run lean and have low power. That assumes it was working and the mixture is adjusted accordingly.

[DMC5180]

The frequency valve has a low rate of failure. If it isn't buzzing it is usually a wiring or adjustment problem. If the valve isn't buzzing the motor would run lean and have low power. That assumes it was working and the mixture is adjusted accordingly.
So your saying if the FV doesn't operate ( releasing system pressure ) you will have a high system pressure making it harder for the metering flap to push down relative to airflow volume?

[Bitsyncmaster]

Jumper the RPM relay socket (remove the RPM relay) from the brown wire to the double yellow red wires. Your frequency valve should buzz.

I use that procedure to remove rest pressure. It takes about 60 seconds of buzzing but when the rest pressure is gone that buzz changes "tune".

That would also prove your frequency valve is working. So verify you have rest pressure (tap the air plate) do the procedure, now verify no rest pressure (tap that air plate again).

[DMCMW Dave]

Jumper the RPM relay socket (remove the RPM relay) from the brown wire to the double yellow red wires. Your frequency valve should buzz.

That would also prove your frequency valve is working. So verify you have rest pressure (tap the air plate) do the procedure, now verify no rest pressure (tap that air plate again).

This buzzing with the engine off/jumped should correspond to 45 dwell reading. If you get the reading and no buzz, once you've had gas in the system whack the frequency valve sharply a couple of times and very often it will free up (the valve is stuck)(this is common on long-dead cars, not cars that have been operating correctly until recently). If you get no reading (i.e. reads 85-ish), troubleshoot the electronics including bulkhead wiring and the large connector on the Lambda ECU.

[OverlandMan]

Jumper the RPM relay socket (remove the RPM relay) from the brown wire to the double yellow red wires. Your frequency valve should buzz.

I use that procedure to remove rest pressure. It takes about 60 seconds of buzzing but when the rest pressure is gone that buzz changes "tune".

That would also prove your frequency valve is working. So verify you have rest pressure (tap the air plate) do the procedure, now verify no rest pressure (tap that air plate again).

I have rest pressure best I can tell. There is some resistance on the air plate after running the fuel pump.

I haven't done the frequency valve test yet but will tonight or tomorrow. I tried to start it again last night and it wouldn't stay running. I sprayed some carb cleaner (just a little) into the air plate/mixture unit. I then started the car and it ran for a few seconds then started sputtering and died a few seconds later. It's acting like it's starved of fuel in some form or fashion.

I first thought maybe the fuel pump pickup line in the tank was collapsing but I'm not so sure. I never could locate the PPV (primary pressure valve). Is it part of the fuel dist assembly or a separate component altogether?

[Bitsyncmaster]

PPV is part of the fuel distributor. When you remove the air cleaner you can see a large nut on the front right hand side. You remove that nut and the parts to the PPR (primary pressure regulator) are inside. A spring, shims, and piston with and O-ring on that piston is the one you need to check for chips in the O-ring.

It seems the original O-rings hold up pretty good to our gas but there were some replacements that would only last less than a year.

[OverlandMan]

PPV is part of the fuel distributor. When you remove the air cleaner you can see a large nut on the front right hand side. You remove that nut and the parts to the PPR (primary pressure regulator) are inside. A spring, shims, and piston with and O-ring on that piston is the one you need to check for chips in the O-ring.

It seems the original O-rings hold up pretty good to our gas but there were some replacements that would only last less than a year.

Gotcha. That's what I needed to know. Thanks for the clarification. I'll check this out tonight. Busy weekend and no time to work on the car.

[David T]

Gotcha. That's what I needed to know. Thanks for the clarification. I'll check this out tonight. Busy weekend and no time to work on the car.

Try not to take the PPR apart. Once you do you can damage the "O" rings trying to put it back together.

[OverlandMan]

Try not to take the PPR apart. Once you do you can damage the "O" rings trying to put it back together.

OK then how does one inspect the PPR for possible damage without taking it apart?

[mluder]

OK then how does one inspect the PPR for possible damage without taking it apart?

The o-ring on question is on the very tip of the assembly. I think what David is suggesting is do not take the entire assembly apart - rather try to remove it as one piece. Often this is difficult as teh "cap" piece that holds the o-ring sometimes stays inside the housing. Min did and I had to use a probe to extract it.

Once removed, the o-ring can easily be replaced. Just make sure you have the correct size and use one made of viton which will hold up to gasoline. Rubber or neoprene will not.

Cheers
Steven

[David T]

The o-ring on question is on the very tip of the assembly. I think what David is suggesting is do not take the entire assembly apart - rather try to remove it as one piece. Often this is difficult as teh "cap" piece that holds the o-ring sometimes stays inside the housing. Min did and I had to use a probe to extract it.

Once removed, the o-ring can easily be replaced. Just make sure you have the correct size and use one made of viton which will hold up to gasoline. Rubber or neoprene will not.

Cheers
Steven

If no one has touched the PPR it is unlikely to be the problem. The accumulator is the most likely suspect followed by the check valve and then fuel leaks. The PPR is the last likely thing to suspect. If you do take it apart have new "O" rings to put in it. Don't try reusing the old ones. They swell and when you try to reuse them you will take chunks out of them as you reinstall them and they will leak.

[OverlandMan]

If no one has touched the PPR it is unlikely to be the problem. The accumulator is the most likely suspect followed by the check valve and then fuel leaks. The PPR is the last likely thing to suspect. If you do take it apart have new "O" rings to put in it. Don't try reusing the old ones. They swell and when you try to reuse them you will take chunks out of them as you reinstall them and they will leak.

According to my records, I replaced the fuel accumulator in Feb of 2013. Now this was prior to my fuel system rebuild but I would think it would still be OK. Maybe not though? Thanks for the info.

http://dmctx.blogspot.com/2013/02/fuel-accumulator.html

[David T]

According to my records, I replaced the fuel accumulator in Feb of 2013. Now this was prior to my fuel system rebuild but I would think it would still be OK. Maybe not though? Thanks for the info.

http://dmctx.blogspot.com/2013/02/fuel-accumulator.html

You are right, move on to the next suspect, the check valve by the fuel pump.

[OverlandMan]

You are right, move on to the next suspect, the check valve by the fuel pump.

I have the OEM style pump setup. The pump, baffle screen and all rubber hoses were replaced earlier this year/late last year. I don't think there is a check valve on my setup.

[Bitsyncmaster]

I have the OEM style pump setup. The pump, baffle screen and all rubber hoses were replaced earlier this year/late last year. I don't think there is a check valve on my setup.

The check valve is on the top of the pump where you bolt the hose onto. They rarely go bad on the old style pumps.

[OverlandMan]

Thanks to Dave @ DMCMW. He took the time to talk to me about this yesterday. What we came up with is to look at 2 areas, the PPR and the WUR. Since the o-ring in the PPR is the cheaper and easier of the 2 areas, I started there. I understand there is an o-ring buried up in there but for the life of me I couldn't see it even with a flashlight (fuel dist still attached to car). I did manage to remove the PPR and find the other side (?) of it. I've attached a picture. Is the o-ring in question one of the 2 rubber bands connected to the components in this picture or is there another o-ring further in there? I did take the big 19mm dual line out (FV and return) to try and see if I could get to it there. I did see a seal facing that side (perpendicular to the PPR channel). I didn't try to remove this for fear of damaging the fuel dist.

35267

My next question is about adjusting the CO. I perused the how-tos and FAQs yesterday but didn't see a write-up on this. If I have to replace the WUR or fuel dist, Dave said an adjustment will likely be necessary. I assume this is where the dwell reading/measurement discussed earlier in this thread comes in. I think I understand the process of reading the dwell but where is the adjustment for the CO? The three screws on the front of the mixture unit were what I thought was the adjustment but apparently that's not the case and I should be looking for an allen-head screw somewhere on the mixture assembly I assume?

Thanks to all for your help. I feel like I'm close here.

[Bitsyncmaster]

The black ring on the far left side of your photo is the O-ring that makes the PPR work or not. The other o-rings never fail and I think would work even without them.

It looks like your O-ring is quite swelled or somebody put the wrong one on.

[David T]

Thanks to Dave @ DMCMW. He took the time to talk to me about this yesterday. What we came up with is to look at 2 areas, the PPR and the WUR. Since the o-ring in the PPR is the cheaper and easier of the 2 areas, I started there. I understand there is an o-ring buried up in there but for the life of me I couldn't see it even with a flashlight (fuel dist still attached to car). I did manage to remove the PPR and find the other side (?) of it. I've attached a picture. Is the o-ring in question one of the 2 rubber bands connected to the components in this picture or is there another o-ring further in there? I did take the big 19mm dual line out (FV and return) to try and see if I could get to it there. I did see a seal facing that side (perpendicular to the PPR channel). I didn't try to remove this for fear of damaging the fuel dist.

35267

My next question is about adjusting the CO. I perused the how-tos and FAQs yesterday but didn't see a write-up on this. If I have to replace the WUR or fuel dist, Dave said an adjustment will likely be necessary. I assume this is where the dwell reading/measurement discussed earlier in this thread comes in. I think I understand the process of reading the dwell but where is the adjustment for the CO? The three screws on the front of the mixture unit were what I thought was the adjustment but apparently that's not the case and I should be looking for an allen-head screw somewhere on the mixture assembly I assume?

Thanks to all for your help. I feel like I'm close here.

Now that you have taken the PPR apart you may as well replace the "O" rings. The WUR controls the fuel mixture during warm-up and makes it richer. If you replace it you do not have to adjust the mixture screw. If you replace the fuel distributor you WILL have to adjust the mixture screw. That adjustment is the very LAST thing you do. Before that you must make sure everything else is working as it should. The 3 screws on the front should all be LIGHTLY seated closed. Rarely will you be able to "adjust" your way out of problems. You do not start replacing things because they are cheap. The theory of troubleshooting is to understand the problem, know the possible causes and test (or replace) the parts that could be the possible causes. The check valve on the fuel pump can go bad and it isn't expensive. You can also have leaks in the fuel system but you usually KNOW about them. Hard not to notice the smell and see the fuel leaking.

[OverlandMan]

Now that you have taken the PPR apart you may as well replace the "O" rings.
All I did was remove it and follow Dave Swingle's advice. So there are 2 o-rings to replace then and not just the one? I see two on the components I have pictured and I assume these are the 2 in question here.


The WUR controls the fuel mixture during warm-up and makes it richer. If you replace it you do not have to adjust the mixture screw. If you replace the fuel distributor you WILL have to adjust the mixture screw. That adjustment is the very LAST thing you do. Before that you must make sure everything else is working as it should.

I'm aware of what the WUR does, especially after my call with Dave S yesterday. He indicated the WUR is NOT a plug and play component and an adjustment would LIKELY be necessary.

Where is the mixture screw? Nobody has answered that yet? I'm not making any adjustments at this time but would like to know for future ref.


The 3 screws on the front should all be LIGHTLY seated closed.

Dave echoed your statement about the 3 screws on the front.


Rarely will you be able to "adjust" your way out of problems. You do not start replacing things because they are cheap. The theory of troubleshooting is to understand the problem, know the possible causes and test (or replace) the parts that could be the possible causes.

No offense David T but your statements here are a little insulting. I'm aware of how the troubleshooting process works. I've been trying to correct this problem for months now (working when I can on it as I'm a busy person). I'm reaching out to the community for guidance on specific problems, which I have laid out in great length earlier in this thread. If someone with more knowledge than I relative to these cars (ie: a parts vendor and/or service group) recommends a couple of tests, I'm going to adhere to that advice. I just want to find the problem(s) and correct them.


The check valve on the fuel pump can go bad and it isn't expensive. You can also have leaks in the fuel system but you usually KNOW about them. Hard not to notice the smell and see the fuel leaking.

The pump is brand new as previously indicated. There are no external leaks in the system as my garage does not smell like gasoline thankfully.

[OverlandMan]

The black ring on the far left side of your photo is the O-ring that makes the PPR work or not. The other o-rings never fail and I think would work even without them.

It looks like your O-ring is quite swelled or somebody put the wrong one on.

OK - well I will see about replacing that ASAP. David T mentioned "o-rings" do I need to replace the other rubber band/ring in the picture or should it be left alone?

[Bitsyncmaster]

OK - well I will see about replacing that ASAP. David T mentioned "o-rings" do I need to replace the other rubber band/ring in the picture or should it be left alone?

I would just leave the others as is.

[OverlandMan]

I would just leave the others as is.

Perfect, thanks. BTW - can you tell me where the mixture adjustment screw is located? I picture is worth a thousand words. 8)

[Bitsyncmaster]

Perfect, thanks. BTW - can you tell me where the mixture adjustment screw is located? I picture is worth a thousand words. 8)

On the top, front of the fuel distributor. There should be a plug in the access hole. You need a 3mm hex (allen) wrench to adjust it.

[David T]

On the top, front of the fuel distributor. There should be a plug in the access hole. You need a 3mm hex (allen) wrench to adjust it.

Went back and read the posts from the beginning. Exactly what did you do when you say you "rebuilt" the fuel system? From all of your posts it sounds like you are running lean. Either the frequency valve is not functioning, the mixture adjustment is off, or you have some plugged fuel injectors. Get out your Workshop Manual and go to D:01:05 and D:04:02 to see the mixture screw. The adjustment procedure is D:04:01

[OverlandMan]

Went back and read the posts from the beginning. Exactly what did you do when you say you "rebuilt" the fuel system? From all of your posts it sounds like you are running lean. Either the frequency valve is not functioning, the mixture adjustment is off, or you have some plugged fuel injectors. Get out your Workshop Manual and go to D:01:05 and D:04:02 to see the mixture screw. The adjustment procedure is D:04:01

Here's what I've replaced:


Fuel pump (OEM type)
Fuel pump hoses (in tank & external tank to metal lines)
Fuel pump baffle screen
Fuel pump boot
Fuel filter
Fuel accumulator kit (DMCH)
All new fuel lines (kit from DPI)
Fuel injector boot seals
Fuel injector clips
Banjo bolts and copper washers
Replaced 2 injectors after flow testing (used)


I've flow-tested the injectors a few times and the volumes are all identical now. Dave S indicated I should get 6oz in 60 sec with air plate fully depressed. I've not tested that yet but everything else looks good on the injectors.

I had a stuck plunger on my fuel dist that I was able to unstick without too much fuss. I suspect this was from sitting for months with old fuel in or around the system.

Speaking of old fuel, I completely drained and cleaned the tank and purged the system late last year. I added fresh gas with an Ethanol stabilizer this spring. I only put about 1/8 tank as I don't want the gas spoiling again in large quantity.

The WUR, Fuel Dist, & FV are original and untouched. When I am able to make the car run, it struggles until it gets warmed and if you give it any throttle it will die or stumble worse. Once the engine warms it sounds great and will rev up fine. Dave S mentioned that I should probably test drive it to see if the power is OK but I want to get the starting issue resolved first as I'm afraid of getting stranded as things sit today.

Dave said it was likely either the PPR (o-ring leaking gas back to the return side and not giving enough to start the engine) and/or the WUR causing it to run too lean which would yield the symptoms I've described.

[David T]

Here's what I've replaced:


Fuel pump (OEM type)
Fuel pump hoses (in tank & external tank to metal lines)
Fuel pump baffle screen
Fuel pump boot
Fuel filter
Fuel accumulator kit (DMCH)
All new fuel lines (kit from DPI)
Fuel injector boot seals
Fuel injector clips
Banjo bolts and copper washers
Replaced 2 injectors after flow testing (used)


I've flow-tested the injectors a few times and the volumes are all identical now. Dave S indicated I should get 6oz in 60 sec with air plate fully depressed. I've not tested that yet but everything else looks good on the injectors.

I had a stuck plunger on my fuel dist that I was able to unstick without too much fuss. I suspect this was from sitting for months with old fuel in or around the system.

Speaking of old fuel, I completely drained and cleaned the tank and purged the system late last year. I added fresh gas with an Ethanol stabilizer this spring. I only put about 1/8 tank as I don't want the gas spoiling again in large quantity.

The WUR, Fuel Dist, & FV are original and untouched. When I am able to make the car run, it struggles until it gets warmed and if you give it any throttle it will die or stumble worse. Once the engine warms it sounds great and will rev up fine. Dave S mentioned that I should probably test drive it to see if the power is OK but I want to get the starting issue resolved first as I'm afraid of getting stranded as things sit today.

Dave said it was likely either the PPR (o-ring leaking gas back to the return side and not giving enough to start the engine) and/or the WUR causing it to run too lean which would yield the symptoms I've described.

At this point all you have is a warm-up problem. Drive the car or at least warm it up in your driveway for about 20 minutes till the cooling fans cycle once. Drive it around, it should be fine. Replace the warm-up regulator AKA Control Pressure Regulator. They can also be rebuilt and calibrated. DO NOT mess with the mixture adjustment, it won't help with your warm-up problem. Before replacing the CPR make sure the vacuum hoses are all hooked up correctly and not leaking.

[DMC5180]

Before you mess with the WUR, make sure you have 12v at the electrical connector. I had a situation once where chassis side bulkhead connector power wire (yellow/red) pin had pushed back in the housing losing its connection.

[David T]

Before you mess with the WUR, make sure you have 12v at the electrical connector. I had a situation once where chassis side bulkhead connector power wire (yellow/red) pin had pushed back in the housing losing its connection.

Even with that it will still warm up, it will just take longer. One of the common problems with the WUR aka CPR, is the element inside and the wiring burns up and no longer functions.

[DMC5180]

Even with that it will still warm up, it will just take longer. One of the common problems with the WUR aka CPR, is the element inside and the wiring burns up and no longer functions.

Agreed, but it is just a long shot worth verifying power through the plug.

[Bitsyncmaster]

If the mixture is miss adjusted, that would also affect the mixture during warm up. The WUR regulator is calibrated expecting the mixture is properly adjusted with the warm engine and the frequency valve is open loop running at 50% PWM.

[OverlandMan]

I replaced the WUR and the PPR o-ring last night. Still no change at this point. I'm going to try and start it again later today but certainly frustrating. For grins and based-off other threads on here, I picked up a screen door spring to put in my pickup hose in the tank. But I figured if its collapsing the pump would be whining pretty noticeably while cavitating.

I did notice a tiny rubber plug on the front of my fuel distributor so I assume this is the CO mixture adjustment. And I'm guessing the plug means it hasn't been molested.

[DMCMW Dave]

I did notice a tiny rubber plug on the front of my fuel distributor so I assume this is the CO mixture adjustment. And I'm guessing the plug means it hasn't been molested.

A metal plug means that nobody has messed with it. A rubber plug/golf tee/chewing gum etc. means that someone has been in there.

[OverlandMan]

A metal plug means that nobody has messed with it. A rubber plug/golf tee/chewing gum etc. means that someone has been in there.

Thanks Dave. I'll go back and look again to verify. I'm pretty sure I was looking at a rubber plug near the front of the fuel dist.

I've been under the weather since Saturday. Now that I'm on meds, I'm starting to get better so hopefully I can get back to work on this towards the end of this week.

[OverlandMan]

Tonight I found a suspicious issue. My newly replaced fuel pump pickup line was kinked likely limiting the flow. I imagine this would have cause low pressure on the inlet side of the fuel dist if I had a gauge on it.

That said, I bought a 9/16" screen door spring and started trying to push it through the line but it seems a bit too large. My question here is do I need to put the spring all the way through the line (lots of bends) or just the area that was kinked (the last bend going into the bottom of the pump)?

[SS Spoiler]

If you stretch the spring way out the diameter will get
smaller and might slip right in. No need for a solid reenforcement.
Cut it to length and your golden.

[Bitsyncmaster]

Be sure your spring ends are bent in so no sharp ends can cut into the hose. I had a spring in my pickup hose but removed it when I bought a new pickup hose.

[penciltester]

May or may not help but check your grounds in the engine bay. Attached to the intake manifold right hand upper corner, towards the firewall, this will jack with your FV amongst a good amount of other things.

[OverlandMan]

Be sure your spring ends are bent in so no sharp ends can cut into the hose. I had a spring in my pickup hose but removed it when I bought a new pickup hose.

So I cut 2 pieces for re-enforcement and filed down the sharp points so as not to cut the hose. I put it all back together and still can't get it to start. Same symptoms as prior. I'm beginning to think it's the fuel distributor. I'm debating whether or not to spend more money on a pressure gauge.

I think the next step here is for me to get it running again with all the fiddly-ness if I can and then take a dwell measurement.

[dn010]

I saw your message in the other post about B-12 and soaking the Fuel Distributor. I would be weary of soaking it in anything- I found certain O-rings in mine were ruined and all I had done is run regular fuel through it and let it sit periodically - I had to rebuild my FD at that point. However, both times I had a bad fuel distributor, the symptom was running extremely rich to the point raw fuel was dripping from the exhaust.

I know it may be a long shot but ultimately the best would be to find someone who has a known good spare FD that is willing to let you swap out just to confirm that is the problem.

A few other thoughts: back when I was running K-Jet and the original engine, I had an issue where I couldn't get the engine running unless I held the meter plate open with a screw driver and sometimes needed to spray starting spray. My first issue was bad bulkhead connections - they needed to be cleaned and then things started working better. The second issue is that one of the steel vacuum pipes that run from the engine to the front of the car developed a hole and I had a massive vacuum leak. I never knew this was a problem until I removed the frame from the car. Maybe you can try to plug your main vacuum connection and see if that makes any difference?

[bfloyd]

I had an issue where I couldn't get the engine running unless I held the meter plate open with a screw driver and sometimes needed to spray starting spray.

That is exactly what my car is doing. In order to start it, I need to hold the metering plate open just a little in order for it to start. Once it starts and warms up, everything works fine. I just replace all of my vacuum lines with a new silicone set, so hopefully I don't have a leak anywhere.

[OverlandMan]

That is exactly what my car is doing. In order to start it, I need to hold the metering plate open just a little in order for it to start. Once it starts and warms up, everything works fine. I just replace all of my vacuum lines with a new silicone set, so hopefully I don't have a leak anywhere.

Barry, any update on this? I had ruled-out vacuum leak(s) as the culprit because the car runs fine once it is able to run. It's the getting it to run part that is such a beating. Is this failed logic?

Does someone make a complete set of vacuum lines? I've replaced a few of the 5/32" lines but that's about it.

[bfloyd]

I actually changed out 3 of my 6 injector seals today. I did the easy ones first (1-2-3), and while I was at it, I did the injector spray test in 20 oz. plastic bottles. Jumped the RPM relay, pressed down on the metering plate and the injectors all sprayed beautifully. I was actually impressed. I'm off from work on Monday night, and plan to do the others, and also replace the blanking cap (#101112) on the carbon canister that crumbled apart while I was working on the engine bay.

I bought John Hervey's full set of silicone lines for the engine bay, and they were very easy to install. Having a numbered diagram with numbered hoses makes it easy. Only vacuum lines I didn't replace go up toward the front of the car.

[OverlandMan]

Alright so I removed my fuel distributor again, soaked it in a small bath of acetone for maybe an hour or two at the most. I also soaked my banjo bolts in parts cleaner as a few of them had some gunk build-up. I put it all back together last night. Now when I try to start the car it sputters and tries to run but rough and it never fully catches to run on its own.

My thoughts at this point to replace the fuel distributor. If anyone has a spare known-good fuel dist they wouldn't mind loaning out for a couple of weeks, that would help me tremendously. Else I'll likely be buying one outright soon.

Also, in the pic below, is the circled piece the CO adjustment "plug"? I still don't know where the heck it is.

35856

[dn010]

I know the effects of acetone on plastics, but not sure how much they may make O rings swell or what not so you might have some damage there.

As for the CO adjustment, what you have circled is where the adjustment screw is. There should be (or have been) a rubber plug for that hole. It looks like you have the anti-tamper component still installed on yours. In the manual it details how to remove it.

[bfloyd]

I'm still dealing with the same issue. If I crack the metering plate open just a little, it'll fire up every single time when cold. When it's warm after running for a while it'll fire right up the first time. I've read here on the forums that it could be a variety of things from a sticky plunger / piston in the fuel distributor, a faulty thermotime switch not triggering the cold start valve, vacuum leak, loose ground connections, etc.

I think I've ruled out the vacuum leak thing in the engine bay with all new silicone lines, although there might be a leak somewhere else that I can't see.

I pulled the cold start valve out on Monday night and placed it in the neck of a 20oz. plastic bottle while my son turned the key to crank the engine. As soon as he engaged the starter, the cold start valve fired the fuel and shot the bottle half-way across the garage. That works.

Ruling those two out, it leaves me with the fuel distributor. With no key in the ignition, I can push down on the metering plate with no resistance and it just bounces up and down - telling me the piston/plunger is lodged up in the body of the distributor. As soon as I turn the key and the fuel pump pressurizes the system, the plunger/piston is pushed back down and there is solid resistance when trying to push the air metering plate down. Looks like I'm going to need to pull the distributor again and clean out the piston and it's cylinder with acetone one more time.

Once the engine does start, it runs weak and a little rough for about a minute or two then the sound of the engine changes, it settles down, and it has full "revving" power. I think I might have a "sticky throttle linkage" thing going, since when you let off the gas the screws that engage the idle air microswitch never fully contact the switch vane. I can press the switch vane with my fingers and the RPM's jump back down below 1K.

We are SO dang close to getting this right.... just a gremlin or two left to tackle.

[Horsebox]

I wouldn't worry too much about the seemingly stuck plunger when you push the metering flap down. Mine does this too, maybe not ideal, but once control pressure sits on the top of the plunger it drops right down. The car starts and runs fine hot or cold. I think in later KE-jet systems they installed a spring to help the plunger drop down again.

Sounds to me like you're running lean, which your engine won't tolerate when cold, but you get away with it when all warmed up. I would get access to your fuel mixture screw and turn it clockwise a quarter turn and I bet it starts better.

[bfloyd]

Would the oxygen sensor come into play anywhere in this?

I ordered the engine "Major Service Kit" from DMCH earlier this Spring, and the only thing I haven't gotten around to installing / replacing is the O2 sensor (Lambda Sensor #101069). I suspect the one on the car is the original that came on the car, but I've been putting off swapping it out since it looks pretty rusted in place. I haven't attempted to remove it yet, but i guess it can be the next thing on the list.

[Horsebox]

Can't you adjust the idle speed microswitch screws so that they actuate the microswitch? Is your throttle spool properly sticky or is it simply that the microswitch isn't quite triggered when the throttle is let go?

On the fuelling side, you could always rig up a switchable 12v source to the cold start valve so that it is constantly firing when "on", which will prove if it's a fuelling problem or not.

Good luck, I understand your frustration! And I agree it sounds like you're nearly there.

[Horsebox]

Forget about lambda at this stage. It is just fine trimming of the fuelling to pin it to stochiometric.

Can you confirm if your frequency valve is buzzing though? This is important.

[Horsebox]

If I were you I'd get hold of a multimeter with duty cycle capability. Shouldn't be too expensive. You want to measure the duty cycle of your frequency valve, before you start playing with the all powerful mixture screw. With a trashed or disconnected oxygen sensor it should be 50% bang on, a default setting if you like. It may read 60% for a minute or so as the engine warms up, but quickly settle to 50%.

Ultimately though you will have to pay a garage to measure the primary and control pressures, or buy the equipment and do it yourself. If your primary or control pressures are wrong and you don't know it, fiddling with the lambda system is like pissing against a gale (sorry to be crude! I learnt the hard way :-))

[OverlandMan]

Well ~20 days have passed and I still have yet to get anywhere with this. Now mind you I haven't messed with it much at all. I did purchase a dwell meter. I've made a checklist and I'm going to see about checking the frequency valve operation first. I'm not sure if I've ever heard it "buzz" like everyone mentions.

The last time I tried to start the car (maybe a couple weeks ago) it would try to start and stumble really hard but never fully catch enough to run. This is different than when I first started this thread. Back then it would fire up and run for a second or two on the CSV.

I have not taken the metal plug out of the CO adjustment on the mixture unit. I read the procedure in the manual but not sure I fully understand. They said to take the mixture unit off the car and invert in a vice and use a nail or similar cut to a specific length. Is that really necessary?

[OverlandMan]

I figured out the plug for the mixture adjustment the hard way. I removed the mixture unit from the car and set it on my work bench. I split the mixture unit from the bottom where I had previously replaced the paper seal. I actually popped out the mixture adjustment from the arm on the unit first. I carefully tapped it back in and changed the nail direction and popped out the plug with ease after that. I hope I didn't do any damage.

With the plug out, I then put the unit back together and mounted everything back up on the car. Without any adjustment I tried to start the car and it behaved the same way it has been. Lots of sputtering but no running. I then made a very slight clockwise adjustment and tried again. Same traffic. Another slight clockwise adjustment and she fired right up. (slight = 1/4 turn or less)

Just for grins I went out the next day and it fired right up again with one turn of the key.

I did pick up an actual dwell meter last week so I have that hooked-up now and plan on taking some readings and trying to adjust the mixture properly. I'm glad I got it running and starting but now I'd like to tune it up and make it right.

[OverlandMan]

OK I'm resurrecting this thread because my car is still not right. Since my last post, I've cleaned and inspected the VOD (details here: http://dmctalk.org/showthread.php?12703-VOD-Question).

I have also replaced the gas (~1yr old or less) with fresh gas.

I have swapped out the fuel distributor for a known good unit from DPI.

I have also swapped out the upper mixture unit (still have the old one).

The problem is the car starts rough and runs like crap. It won't stay running and I smell unburned fuel in the exhaust, which I assume means its too rich. I also see some black-ish smoke (not white or blue) in the exhaust. The air-plate on the upper mixture unit also makes a gasping air sound when the idle is low.

Prior to rebuilding the fuel system (2+ years of tinkering now), the car ran great. This is why I rebuilt the fuel system: http://dmctx.blogspot.com/2013_09_01_archive.html

I took a video of the car running bad tonight but it's too large to upload so I'm going to compress and trim it up tomorrow and try again.

[OverlandMan]

I got the car running great now but only when I jumper the RPM relay socket. If I plug in the relay, it runs like crap (too rich). Would this be the WUR? I replaced the WUR last year from DHCMW and recall Dave saying they had some high failure rates on the rebuilds. How can I isolate the WUR for testing this theory?

[DMC5180]

Too isolate, just unplug it. But you are only disabling the heater circuit. Sounds more like you have a lambda circuit issue to me.


Dennis

[Bitsyncmaster]

I got the car running great now but only when I jumper the RPM relay socket. If I plug in the relay, it runs like crap (too rich). Would this be the WUR? I replaced the WUR last year from DHCMW and recall Dave saying they had some high failure rates on the rebuilds. How can I isolate the WUR for testing this theory?

Your mixture needs adjusting. You must be jumping the pump circuit only. The RPM relay turns on a few things, pump and the lambda system.

If your just jumping the pump the frequency valve is not powered and your mixture changes.

[OverlandMan]

Your mixture needs adjusting. You must be jumping the pump circuit only. The RPM relay turns on a few things, pump and the lambda system.

If your just jumping the pump the frequency valve is not powered and your mixture changes.

I roughed-in the mixture with a method I read about on here somewhere. The process was, pull the injectors like your doing a flow test and put them in jars/bottles, then with the fuel pump running turn the mixture screw until the injectors spray start to spray a tiny bit, then back off to the point where they don't. I know this isn't the final setting but I wouldn't think there would be such big discrepancy between the RPM relay triggering those other systems and the fuel pump running solo.

The FV is probably the last remaining item in my fuel system I have not replaced but I can here it buzzing. When I pull the WUR electrical connection and turn on the ignition (but not the car yet) the FV buzzes in a continuous loop versus just one cycle.

How should I adjust the mixture in this scenario? Do the previous method I described but instead of jumpering the pump only, use the RPM relay? Will it work that way?

I do have a dwell meter and was going to get the final setting made after everything was in place like it should be.

[DMC5180]

Just turning on the ignition only makes the idle speed motor hum / buzz. The engine must be running for the FV to buzz. It is powered via the rpm relay which intern requires a coil impulse signal from cranking/ running.


Dennis

[Bitsyncmaster]

As Dennis said, the FV should only buzz with the engine running. Maybe your just hearing the idle motor buzz.

Yes you use the dwell meter to get the mixture dialed in when everything is working.

[OverlandMan]

As Dennis said, the FV should only buzz with the engine running. Maybe your just hearing the idle motor buzz.

Yes you use the dwell meter to get the mixture dialed in when everything is working.

OK must be... good info. So how would you proceed? If you think its just my mixture, and knowing I already set it as previously described... what's the thought process there? If I start the car using the RPM relay (newly replaced by the way), it runs terrible and I smell raw gas and the exhaust spits.

[Bitsyncmaster]

OK must be... good info. So how would you proceed? If you think its just my mixture, and knowing I already set it as previously described... what's the thought process there? If I start the car using the RPM relay (newly replaced by the way), it runs terrible and I smell raw gas and the exhaust spits.

Hook up your dwell and install the good RPM relay. Your dwell will probably read at the max (85 deg) or min (15 deg) on the four cylinder scale. So make small adjustments until you get it in the 40 deg area.

[OverlandMan]

Hook up your dwell and install the good RPM relay. Your dwell will probably read at the max (85 deg) or min (15 deg) on the four cylinder scale. So make small adjustments until you get it in the 40 deg area.

Thanks Dave. If its on the max or min like you said, which corresponding way to turn the adjustment?

[Bitsyncmaster]

Thanks Dave. If its on the max or min like you said, which corresponding way to turn the adjustment?

Good question, I think clockwise increases the dwell but you can just move about a 1/4 turn one way and if that does not work, try the other way. Your probably within a half turn anyway.

You should test your dwell meter by pressing the WOT switch and it reads 54 deg. Adjust the mixture after the engine has warmed up. Dwell will not go closed loop until engine has warmed (about 3 min running).

[OverlandMan]

Good question, I think clockwise increases the dwell but you can just move about a 1/4 turn one way and if that does not work, try the other way. Your probably within a half turn anyway.

You should test your dwell meter by pressing the WOT switch and it reads 54 deg. Adjust the mixture after the engine has warmed up. Dwell will not go closed loop until engine has warmed (about 3 min running).

I don't want to warm the car up with the raw gas, black smoke issue so I guess I'll warm it up with the relay socket jumped (fuel pump only), then turn off car, install RPM relay, turn car back on, and go to dwell setting. I recently replaced the O2 sensor and don't want to foul it, the plugs, or do any other damage in the crappy/rich running state with the RPM relay in.

Where is the WOT switch? I think I know but want to be sure.

Thanks for all the info Dave. I'll report back my findings in the next day or two.

[DMC5180]

WOT switch is what the throttle spool hits at full rotation. Flap switch (white)


Dennis

[OverlandMan]

WOT switch is what the throttle spool hits at full rotation. Flap switch (white)


Dennis

Thanks Dennis

[flux3d]

Just been reading through this whole thread and it occurred to me that you might have a problem with your idle speed motor. When I got my car I had to keep my foot on the gas until the car warmed up or it'd just die, similar to what you've described. After chasing Mt trail for ages I tracked the fault to the idle speed ecu. This controls the Isle speed motor using an ossoleting pulse. One of these outputs was blown, causing the idle speed motor to close, starving the engine of air until it warmed up. Rebuilding the ecu solved the problem right away.

By the way that's my video posted at the start of the thread on adjusting the dwell. Hopefully it was useful.

[Jonathan]

Jeff, from a question/comment a few posts ago... you can get the frequency valve to buzz without the engine running and by just jumpering the RPM relay. I've never tried to start or run the engine this way, as I'm not sure what other aspects of the fuel/lambda system would be bypassed or off doing so, but for troubleshooting, it is a good way to turn on the fuel pump and frequency valve. And without the engine running, there's no mistake in knowing what sound the frequency valve makes.

[Bitsyncmaster]

If you carry a backup jumper for the RPM relay, it should have two wires and three pins. Brown wire (battery +) gets jumpered to the white/purple (fuel pump) and brown wire gets jumpered to the double yellow red wires.

You can run the FV with that jumper without the engine running. I do that to release rest pressure if I need to work on fuel lines.

[OverlandMan]

I've only been jumpering the fuel pump (one wire between 2 terminals in the socket - brown and white w/ purple tracer). Will running the FV effect the mixture? I thought it just metered the outbound pressure on the return line from the FD back to the tank.

[David T]

I've only been jumpering the fuel pump (one wire between 2 terminals in the socket - brown and white w/ purple tracer). Will running the FV effect the mixture? I thought it just metered the outbound pressure on the return line from the FD back to the tank.

Refer to your Workshop Manual D:04:07 - :10 for an explanation of the Frequency valve and the Lambda system. It basically enriches the mixture, fine-tuning it to make the combustion as efficient as possible. By only running the fuel pump (and not powering the Lambda system) you have to over-adjust the mixture screw to make up for the lack of fuel that should be fed by the Lambda system. Once you get the Lambda system and the frequency valve working you will have to lean the mixture using the dwell meter to set the duty cycle of the frequency valve.

[OverlandMan]

Refer to your Workshop Manual D:04:07 - :10 for an explanation of the Frequency valve and the Lambda system. It basically enriches the mixture, fine-tuning it to make the combustion as efficient as possible. By only running the fuel pump (and not powering the Lambda system) you have to over-adjust the mixture screw to make up for the lack of fuel that should be fed by the Lambda system. Once you get the Lambda system and the frequency valve working you will have to lean the mixture using the dwell meter to set the duty cycle of the frequency valve.

OK makes sense. Hopefully will be able to work on it this weekend and report back success. Thanks to all who have replied!

[flux3d]

Have you checked the idle speed motor at all? As I said I had a very similar situation to yours and it helped after checking all of the other potential problems you and others have mentioned. Get a multimeter on the outputs.

This thread goes over checking the idle ecu and motor, with the original poster (not me) having remarkably similar symptoms.

http://www.deloreans.co.uk/forum/archive/index.php?thread-750.html

[OverlandMan]

Have you checked the idle speed motor at all? As I said I had a very similar situation to yours and it helped after checking all of the other potential problems you and others have mentioned. Get a multimeter on the outputs.

This thread goes over checking the idle ecu and motor, with the original poster (not me) having remarkably similar symptoms.

http://www.deloreans.co.uk/forum/archive/index.php?thread-750.html

flux3d, I will check that too! Thanks.

[OverlandMan]

RPM relay installed and car warmed up with cooling fans running. Mixture adjustments don't seem to effect the dwell meter as seen in video. Car sputtered a little black smoke and exhaust liquid when it was cold. After it warmed up those symptoms went away but still smelled a little raw gas smell like its still to rich.

[OverlandMan]

RPM relay installed and car warmed up with cooling fans running. Mixture adjustments don't seem to effect the dwell meter as seen in video. Car sputtered a little black smoke and exhaust liquid when it was cold. After it warmed up those symptoms went away but still smelled a little raw gas smell like its still to rich.

https://vimeo.com/169457855



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[dn010]

Pull the main vacuum line off the passenger intake runner. Put a vac cap on the nipple and then try.

Also, can you confirm what wires you've hooked the dwell meter too?

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[Horsebox]

I don't think you can really tell much with the rubber bung removed from the adjustment screw. I know it's only a small hole but it's a huge vacuum leak. When I had my car plugged into an exhaust gas tester, removing the bung caused a 2% change in CO emissions, way outside what the lambda system can compensate for.

I think you're best off setting the mixture by CO emissions, then plug back in working lambda system and it should trim it nicely. :-)

[David T]

After adjusting the mixture screw you must cover the hole before trying to read the meter. If your adjustments are not having any effect make sure you are in "closed loop". If it still won't adjust you either have the O2 sensor disconnected or it is contaminated. You can try grounding the O2 sensor lead and applying 1.5 volts to it to make sure the Lambda module is working. Refer to D:04:15 in your Workshop Manual. A very small movement of the mixture screw has a big effect on the dwell, you should not have to make large adjustments. If you smell fuel you are running too rich and should be leaning the mixture screw by turning it counter-clockwise. The whole procedure starts on D:04:01. Do you hear the frequency valve buzzing? if not remove and replace the plug to it a couple of times. Make sure it's ground wire is actually connected to ground too.

[OverlandMan]

Pull the main vacuum line off the passenger intake runner. Put a vac cap on the nipple and then try.

Also, can you confirm what wires you've hooked the dwell meter too?

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I grounded the dwell meter to a ground on the intake. The lead wire is connected to the diagnostic plug (lower right corner terminal if looking at it from the back of the car facing towards the front of the car).

I will try the vacuum test like you mentioned tonight.




I don't think you can really tell much with the rubber bung removed from the adjustment screw. I know it's only a small hole but it's a huge vacuum leak. When I had my car plugged into an exhaust gas tester, removing the bung caused a 2% change in CO emissions, way outside what the lambda system can compensate for.

I think you're best off setting the mixture by CO emissions, then plug back in working lambda system and it should trim it nicely. :-)


I will try to get a reading with the mixture screw plugged; didn't really think about that. Thanks.

I'm not sure what you mean by setting the mixture by CO emissions...




After adjusting the mixture screw you must cover the hole before trying to read the meter. If your adjustments are not having any effect make sure you are in "closed loop". If it still won't adjust you either have the O2 sensor disconnected or it is contaminated. You can try grounding the O2 sensor lead and applying 1.5 volts to it to make sure the Lambda module is working. Refer to D:04:15 in your Workshop Manual. A very small movement of the mixture screw has a big effect on the dwell, you should not have to make large adjustments. If you smell fuel you are running too rich and should be leaning the mixture screw by turning it counter-clockwise. The whole procedure starts on D:04:01. Do you hear the frequency valve buzzing? if not remove and replace the plug to it a couple of times. Make sure it's ground wire is actually connected to ground too.



Hey David, what do you mean by "closed loop"? I replaced my O2 sensor last month so it should be OK, I would think.

I'm not sure about the FV buzz. I have terrible hearing. Could you hear it buzzing in my video? It's probably the last thing I haven't replaced in the fuel system.

[David T]

Until the motor warms up the Lambda system will run in open loop, meaning it sets to a fixed value for the dwell. The mixture cannot be adjusted till the Lambda system is responding to the O2 sensor in closed loop. RTFM

[DMC5180]

I takes about 2.5 to 3 minutes of running at idle with a cold engine before it it goes closed loop. Proper adjustments should be done with the engine at full operating temperature with fans cycling at least once.


Dennis

[OverlandMan]

Until the motor warms up the Lambda system will run in open loop, meaning it sets to a fixed value for the dwell. The mixture cannot be adjusted till the Lambda system is responding to the O2 sensor in closed loop. RTFM




I takes about 2.5 to 3 minutes of running at idle with a cold engine before it it goes closed loop. Proper adjustments should be done with the engine at full operating temperature with fans cycling at least once.



OK gotcha. Yes I was testing yesterday (video) with the car fully warmed-up. The thermostat was open and the coolant was passing through the system and the fans running.

[OverlandMan]

https://vimeo.com/173264696

Am I there? This is with the engine fully warm, idle about right, and the pass side vacuum off the intake plugged.

I referenced the service manual and it said 45-55% with a =<10% variance. This shows 40-45% with a =<5% variance.

Wanted to get feedback before I do any further adjusting.


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[David T]

Looks like you are in active closed loop at about the right duty cycle, so, yes, you are "there". You do have the hole over the mixture screw plugged off and the 3 brass crews lightly seated, right?

[OverlandMan]

Looks like you are in active closed loop at about the right duty cycle, so, yes, you are "there". You do have the hole over the mixture screw plugged off and the 3 brass crews lightly seated, right?


Correct. The mixture screw plug is back in place while the meter is being read in the video. The 3 screws are all closed as well.

The car seems to hot and cold start without issue now. The exhaust does not smoke or smell like raw gas like before. The engine does shake a bit a low idle and there is still an occasional miss regardless of engine temp or RPMs, but I'm pretty sure this has been the case since I've owned the car. I'm wondering if the shake/shimmy is worn motor mounts?