Hard start cold or hot but runs good

[northeast dmc]

Ok, in order to get the car started and stay running, I need to get out once it catches, and play with the pressure plate to the fuel distributor and play with the throttle. After doing this for say 45 seconds some times a little longer it will stabilize and I can drive it with no issue, idles a little rich. When I get back shut the car off and try to restart and same thing, maybe slightly harder to get started. I have pulled the fuel pump and cleaned the screens, I have replaced the fuel filter. After replacing I pulled the supply line of off the feul distributor, and hot wired the fuel pump and got all the air out of the system, and had real good fuel flow. When I turn the key on I do not hear the fuel pump come on, I switched the RPM/fuel relay and still nothing. From what I have read shouldnt the pump come on initially when the key is turned on to at least charge the system? The reason for cleaning the screens and filter, is getting what I believe is the bad gas in the return line portion. I originally cleaned the tank, new fuel pump, I have since cleaned the feed line and changed the fuel filter several times. But never considered the return line. But with more than 100 miles I would think that that would be cleaned out. Its all fresh gas, even went to the gas station near me and topped it off. Is there another part of the fuel system that could have an effect on the initial fuel pump operation? Like I said once I can get it running it stays running and drives good. Just dont dare go to store and shut it off.

[Michael]

Sounds like it might be a rest pressure problem. Possibly bad o rings in the primary pressure regulator or completely shot accumulator. Could also be a big fat intake leak, mixture out of adjustment(due to another problem).

When you say "play with pressure plate" I am assuming you mean the metering plate.

[Michael]

I reread your post and I would also check to see if the distributer plunger is stuck.

[northeast dmc]

Sounds like it might be a rest pressure problem. Possibly bad o rings in the primary pressure regulator or completely shot accumulator. Could also be a big fat intake leak, mixture out of adjustment(due to another problem).

When you say "play with pressure plate" I am assuming you mean the metering plate.

Yes the metering plate, and I went out pulled the injectors out hot wired the pump and set the CO screw as close as can be done this way. And voila the car starts right up, I did check the wirs to the pump and other connections. But it starts and restarts good, just a slight hesitation on acceleration. But I am still having an issue with the screens on the fuel pump getting clogged. Is there a way to 'flush' the return lines other than running it and keep cleaning the screens? The acccumulator was/is new. But after all this would I be better off changing it out? Not a lot of fun on my back under the car. Thanks again for the feedback.

[Michael]

If the accumulator is new forget it. It's probably good. When you say your screens are clogging up, what is that? Your fuel filter? Your fuel filter filters the fuel from the pump not the return so if it's getting visibly clogged then you might have some serious contamination in your tank, pick up screen clogged, etc.

You can pull the pump and look into the tank, it should be fairly obvious if your tank is contaminated. If it is dirty, then I would drain and clean the tank and replace the pump and filter. I say replace the pump because if your filter is clogged as quickly as you say, then the damage to the pump may be done. It's hard to find a quality OE setup anymore, so it might be a good time to upgrade to a modern unit.

Once the car is running well enough to go into closed loop, you can adjust your mixture. It's damn near impossible to set it without some type of reading instrument, either a dwell meter or multi meter or exhaust probe.

[Bitsyncmaster]

Some cars will prime with an OE RPM relay and others don't. What causes the prime on OE RPM relays is it sees an ignition pulse after the power is applied to the RPM relay. It is not a designed feature in the OE RPM relays to prime the fuel system.

[northeast dmc]

If the accumulator is new forget it. It's probably good. When you say your screens are clogging up, what is that? Your fuel filter? Your fuel filter filters the fuel from the pump not the return so if it's getting visibly clogged then you might have some serious contamination in your tank, pick up screen clogged, etc.

You can pull the pump and look into the tank, it should be fairly obvious if your tank is contaminated. If it is dirty, then I would drain and clean the tank and replace the pump and filter. I say replace the pump because if your filter is clogged as quickly as you say, then the damage to the pump may be done. It's hard to find a quality OE setup anymore, so it might be a good time to upgrade to a modern unit.

Once the car is running well enough to go into closed loop, you can adjust your mixture. It's damn near impossible to set it without some type of reading instrument, either a dwell meter or multi meter or exhaust probe.

6342763428 I have attached pictures of the screens on the pump and pump housing, the return line dumps into the housing. The fuel in the tank looks good, this is a new fuel pump. And I will use the dwell meter to fine tune the CO screw. It has started easy the bunch of times I tried, and even hot it restarts with relative ease.

[Michael]

Yeah that's not an OE pump assembly but I hope it's not too new because your strainers are picking up a lot of junk. Your tank may be dirty and dirt kills pumps. Sounds like your main problem was cured with a mixture adjustment but you need to figure out why it got so out of whack to begin with. That screw doesn't turn itself so something changed to throw the mixture out to begin with, most likely a vacuum leak but don't dismiss a fuel delivery component. You can compensate a problem with mixture but that doesn't fix it.

[David T]

If, all of a sudden, you have cold start problems you check the cold start valve (and associated parts) and the CPR and it's hoses. If it seems to creep and get worse slowly, you may need a tune-up.

[northeast dmc]

Yeah that's not an OE pump assembly but I hope it's not too new because your strainers are picking up a lot of junk. Your tank may be dirty and dirt kills pumps. Sounds like your main problem was cured with a mixture adjustment but you need to figure out why it got so out of whack to begin with. That screw doesn't turn itself so something changed to throw the mixture out to begin with, most likely a vacuum leak but don't dismiss a fuel delivery component. You can compensate a problem with mixture but that doesn't fix it.


Thanks for the feedback, I am guilty of adjusting it, slightly without using the dwell. And now that I have the timing dialed in and will get the dwell and fine tune the CO adjustment should put me in good shape. And hopefully work through the fuel issue. Then on to getting some of the finer details worked out.

[northeast dmc]

Thanks for the feedback, I am guilty of adjusting it, slightly without using the dwell. And now that I have the timing dialed in and will get the dwell and fine tune the CO adjustment should put me in good shape. And hopefully work through the fuel issue. Then on to getting some of the finer details worked out.

Well the saga continues. I finally emtied the fuel tank, cleaned it out, put fresh gas in ans still crud in the tank. Not sure what I missed. The bigger issue is after I clean the screens on the fuel pump, put it back together it wont acelerate. Starts fine idles fine but cant accelerate, if I get out and manipulate the pressure plate while moving the throttle it will run fine. I am thinking vacuum leak, but why wouldnt it show up initially? This morning I went out started it right up like it always does, drove 7 miles or so shut it off got my coffee, went back out it started right up and yup like every time cant accelerate beyond say 1300 rpm, tach gauge is alittle erratic. Drive home clean the screens, and it wont go beyond the certain rpm. If I let it sit and cool down in the past it will run fine. Is there something heat related that might cause a vacuum leak after it gets hot?
Any help greatly appreciated, would like to get beyond this so I can work on the other items that need attention.

[Michael]

Don't discount the fuel pump being bad or getting low voltage. Next time it exhibits this issue, check your voltage at the pump (possibly a corroded plug or wire splice) and the pressure to the distributer. One of the hallmarks of a pump going out is it fails at temp but runs perfect when cold.

[northeast dmc]

Don't discount the fuel pump being bad or getting low voltage. Next time it exhibits this issue, check your voltage at the pump (possibly a corroded plug or wire splice) and the pressure to the distributer. One of the hallmarks of a pump going out is it fails at temp but runs perfect when cold.

Update, I just drove the car for 15 to 20 minutes non stop, ran fine an occasional hickup, but other than the slight stumble at the low end ran until I got home. I pulled the pump and cleaned the screens, tried to drive again and still the issue with any acceleration. Idle all day, just dont try top go anywhere in a hurry. Relatively new pump and wires, and being I am constantly plugging and unplugging the connections are good. But the point of acting up when hot makes me wonder as if I let it sit and cool down it will run good. hmmm, guess it is time for fuel pressure gauge. What should the pressure be? I can look it up once I get the gauge.

[Rich]

Primary fuel pressure is ~75 psi regardless of temperature or flow rate.


What should the pressure be? I can look it up once I get the gauge.

[northeast dmc]

Primary fuel pressure is ~75 psi regardless of temperature or flow rate.

Thank you.

[northeast dmc]

Update, I just drove the car for 15 to 20 minutes non stop, ran fine an occasional hickup, but other than the slight stumble at the low end ran until I got home. I pulled the pump and cleaned the screens, tried to drive again and still the issue with any acceleration. Idle all day, just dont try top go anywhere in a hurry. Relatively new pump and wires, and being I am constantly plugging and unplugging the connections are good. But the point of acting up when hot makes me wonder as if I let it sit and cool down it will run good. hmmm, guess it is time for fuel pressure gauge. What should the pressure be? I can look it up once I get the gauge.


Well round 2 of updates, last for today. Well did deep cleaning of tank, AGAIN, left pump out, put fuel in and checked tank was crystal clear. Drove to mgas station running as usual, shut it off put about 8 gallons of 91 ethanol free in started it and same result, limped home. Checked the voltage at the fuel pump connection and read 11.5. Went to the back and checked the jumper post and read around 14 volts. Is the voltage reading of 11.5 low enough to cause an issue? I did check the voltage earlier today to verify the positive wire just to be sure and with the car off it read 13 volts. So is pressure gauge my next move, and where do you get the adaptor for the banjo bolts to go to the gauge? If it cools off enough I will try to get a reading at the pump with it cool tonight just for curiosity. Wont get to it until end of the week with work and all. Let me know if I should order the tester, probably cant hurt I assume.

Thanks for the help.

[Rich_NYS]

I wonder if a failing RPM relay would cause that voltage symptom (?)

If we get an affirmative on that, I'll bring you a replacement relay to try.

I'm also planning to get a fuel pressure test kit, but not sure how soon it'll arrive.

[Rich]

I've never used a K-Jet pressure test kit. Here is one that pops up from a web search on those terms:

https://www.amazon.com/Tool-Aid-33865-K-Jetronic-Injection/dp/B0002SR5NU (https://www.amazon.com/Tool-Aid-33865-K-Jetronic-Injection/dp/B0002SR5NU)

I'm sure there are others. Somebody can comment on whether that's a quality tool or not.


So is pressure gauge my next move, and where do you get the adaptor for the banjo bolts to go to the gauge? If it cools off enough I will try to get a reading at the pump with it cool tonight just for curiosity. Wont get to it until end of the week with work and all. Let me know if I should order the tester, probably cant hurt I assume.

[ritztoys]

I've never used a K-Jet pressure test kit. Here is one that pops up from a web search on those terms:

https://www.amazon.com/Tool-Aid-33865-K-Jetronic-Injection/dp/B0002SR5NU (https://www.amazon.com/Tool-Aid-33865-K-Jetronic-Injection/dp/B0002SR5NU)

I'm sure there are others. Somebody can comment on whether that's a quality tool or not.

I'm not a tool reviewer, but this looks very similar to a Bosch unit I have with the "T" fitting & valve, indispensable tool when trouble shooting K-Jet.

Yes, you should buy it....!

[David T]

From your comments it sounds like the problem is intermittent. It would be more likely to be an electrical problem than a fuel problem. A bad (contaminated) O2 sensor is usually less sensitive and acts more slowly. Running too rich for a while can contaminate it. A bad connection or a connector not making good contact in a plug are the most likely suspects.

[Bitsyncmaster]

Well round 2 of updates, last for today. Well did deep cleaning of tank, AGAIN, left pump out, put fuel in and checked tank was crystal clear. Drove to mgas station running as usual, shut it off put about 8 gallons of 91 ethanol free in started it and same result, limped home. Checked the voltage at the fuel pump connection and read 11.5. Went to the back and checked the jumper post and read around 14 volts. Is the voltage reading of 11.5 low enough to cause an issue? I did check the voltage earlier today to verify the positive wire just to be sure and with the car off it read 13 volts. So is pressure gauge my next move, and where do you get the adaptor for the banjo bolts to go to the gauge? If it cools off enough I will try to get a reading at the pump with it cool tonight just for curiosity. Wont get to it until end of the week with work and all. Let me know if I should order the tester, probably cant hurt I assume.

Thanks for the help.

11.5 volts on the fuel pump should work but if your dropping 2.5 volts somewhere you should find out where and fix it. Connectors, bad connections, RPM relay.

Limited engine RPM could be fuel or ignition. Best to do a fuel pressure check for fuel Since it hard to test for marginal ignition.

[David T]

You could also be losing voltage across the inertia switch and the ground circuit. The other thing to check is the plug up inside the washer bottle bucket. Make sure you had the recall done on the inertia switch.

[northeast dmc]

Thank you for all the response, obviously things to look at. One thought as I was talking with a buddy of mine and going through the sequence of events. Is it possible for the frequency valve to be vulnerable to the heat when I shut it off? and would it cause the type of issue I am having? Like i mentioned if I get out and manually manipulate the throttle and the metering plate I can make it run fine, leading me to believe I have sufficient fuel from the pump.I dont recall in thinking back that I hear it when I go to restart after reaching the gas station. Just a shot in the dark.

[Rich_NYS]

I remember there's a test for the FV, jumping pins on the RPM relay socket....like the test for the fuel pump.

Anybody here recall what it is? I remember seeing it in a post from Dave S, I think.

[Bitsyncmaster]

I remember there's a test for the FV, jumping pins on the RPM relay socket....like the test for the fuel pump.

Anybody here recall what it is? I remember seeing it in a post from Dave S, I think.

You can jump the RPM relay connector to power up the FV and lambda but I just use that to remove the rest pressure before I need to pull a fuel hose.

[northeast dmc]

Which wires are used for the FV/Lamba ? I know the ones to power the fuel pump.

[Ron]

+1 on the fuel gauge --You'll need it later anyway. :deviltail:

I'm unclear about the symptoms still being intermittent or not. Assuming it currently acts up only after running a while, the coil may be breaking down. So while waiting on the gauge, I'd try a jumper from the battery (+) to the coil (+), AFTER it acts up to eliminate connections etc for that side. If no luck, maybe ohm out the coil or borrow one for a test next...
Since you keep finding more trash in the fuel, I'd suggest you let the return line dump into a suitable container and recycle it until that is resolved. (Strain it as it goes in...) Assuming the fuel filter isn't getting clogged because the screens are doing their job, you might want to check the screen(s) in the WUR/CPR (and FD). Trash could be packing up in them, until you shut it off relieving most of the pressure... You'll be able to identify this and a lot more with the gauge set.

[Bitsyncmaster]

Which wires are used for the FV/Lamba ? I know the ones to power the fuel pump.

You jumper the large brown wire to the double yellow/red wires and that turns on the FV and lambda ECU. No need to turn on the key. You will hear the FV buzz. It takes about 60 seconds to dump a full rest pressure back to the return line. You will hear the FV buzz change tone when pressure goes to zero.

[Rich_NYS]

~snip~ Assuming the fuel filter isn't getting clogged because the screens are doing their job, you might want to check the screen(s) in the WUR/CPR (and FD). Trash could be packing up in them, until you shut it off relieving most of the pressure... You'll be able to identify this and a lot more with the gauge set.

I like the looks of this assessment....it smells to me like one of Ron's infamous obscure tips that fixes a problem!

[northeast dmc]

+1 on the fuel gauge --You'll need it later anyway. :deviltail:

I'm unclear about the symptoms still being intermittent or not. Assuming it currently acts up only after running a while, the coil may be breaking down. So while waiting on the gauge, I'd try a jumper from the battery (+) to the coil (+), AFTER it acts up to eliminate connections etc for that side. If no luck, maybe ohm out the coil or borrow one for a test next...
Since you keep finding more trash in the fuel, I'd suggest you let the return line dump into a suitable container and recycle it until that is resolved. (Strain it as it goes in...) Assuming the fuel filter isn't getting clogged because the screens are doing their job, you might want to check the screen(s) in the WUR/CPR (and FD). Trash could be packing up in them, until you shut it off relieving most of the pressure... You'll be able to identify this and a lot more with the gauge set.

I recleaned the fuel tank on Sunday and with a suggestion of using the camera to see I did find and clean the deep corner and verified the rest was clean. I am going to order the tester. I have also changed the main fuel filter several times through out this struggle just to be sure nothing getting in the heart of the system. The issue arrise after say 10-15 minute drive. Everytime I shut it off, it restarts and idles fine, its when I try to accelerate that I have the issue. Even after the last cleaning of the tank, I drove to the gas station feeling pretty good, only to have it happen again. If I get out and manipulate the metering plate and the throttle manually it will run fine at any rpm as long as I have the two timed so to speak. It would almost seem like a vacuum leak, but I would think it would be there right from the start, or if it somehow was heat related it would have shown up when I just drove around for 20 minutes. This is what has me thinking the frequency valve not working when I restart it hot and not letting the fuel go back to the tank like it should creating excess pressure in the fuel distributer. Just me stuck on that thought. But the running issue has happened every time I drive and shut it off. But being some what new to this adventure I am all ears and grateful for all the information.

[northeast dmc]

Well, an update, I cleaned and made sure the frequency valve was connected good, drove the car for 20 minutes, shut it off let it sit, and restarted. It did rev up, after stumbling a little, but this is the first that I have been able to at least accelerate after shutting it down when up to temperature. Not sure if the suggestion of the higher octane, ethanol free has anything to do with it, but cautiously optimistic at this point. Will try it again tomorrow and see how it goes.

[Michael]

Another member here who had issues very similar to yours found the culprit to be fuel injectors.

[northeast dmc]

Another member here who had issues very similar to yours found the culprit to be fuel injectors.

Thanks, I did put new injectors in and new seals for them. I have been driving it every day over the weekend put alot of miles on it, the dirty tank issue would appear to be resolved. I still encounter a hesitation after shutting it off, say to get a coffee, which by the way has anyone come up with a cup holder idea? back to the topic, after going in and getting coffee, come back out it restarts quite easily in my opinion, and start out low speed seems fine, then hesitates for 30 seconds maybe aminute as I try to accelerate, then it clears out and runs fine. Cant quite pinpoint the issue. If it sits as it did Saturday while talking to my brother for a period of time it ran good no issue when I restarted it. The only other thing that I have noticed is it seems to be at alightly higher RPM when it is up to temperature, versus when I first start it. I cant tell you as the tach is all over the place, need to pull the binacle and try to get the connection better on the dash. But by ear definitely higher hot versus cold.?????

[Bitsyncmaster]

If you mean idle RPM is higher when the engine is hot, back out your curb idle screw because the idle speed motor may be running out of range. I had that problem even with the curb idle screw backed all the way out. It turned out my deceleration valve springs were bad. So that let to much air into the system and pushed up the idle RPM.

If one of your deceleration springs is bad that may be causing some other problems but most of the bad springs are both are bad or not.

[northeast dmc]

If you mean idle RPM is higher when the engine is hot, back out your curb idle screw because the idle speed motor may be running out of range. I had that problem even with the curb idle screw backed all the way out. It turned out my deceleration valve springs were bad. So that let to much air into the system and pushed up the idle RPM.

If one of your deceleration springs is bad that may be causing some other problems but most of the bad springs are both are bad or not.

Thanks for the information, it does seem like if I push on the throttle plate arm it does decrease the idle, the deceleration valve springs, are these the ones on the throttle plate arm? And if the throttle arm isnt going back due to the weak springs its possible it isnt tripping the microswitch to the idle speed motor? Sorry if my descriptions are off.

[David T]

If, pushing on the throttle arm reduces the idle, the quadrant link (the short link between the throttle spool and the throttle arm) is worn. You can adjust it to force the throttle arm all the way to idle. Getting back to your hesitation/warm up problem, recheck the vacuum hoses and connections to the CPR. If that isn't the problem you may need to have the CPR re calibrated. It is also known as the Warm-up Regulator and acts like a choke on a carbureated car to improve drivabilty till the motor warms up. It also functions as an accelerator pump and delivers a spike of fuel upon acceleration to quickly richen the air/fuel mixture to prevent hesitation.

[Bitsyncmaster]

Thanks for the information, it does seem like if I push on the throttle plate arm it does decrease the idle, the deceleration valve springs, are these the ones on the throttle plate arm? And if the throttle arm isnt going back due to the weak springs its possible it isnt tripping the microswitch to the idle speed motor? Sorry if my descriptions are off.

The deceleration springs are on the throttle plates. To see them you need to pull off the W pipe. I did have a photo of bad springs but it looks like most of my uploaded photos on DMCtalk are not showing up anymore. If the springs have evenly spaced coils of wire then they are good but uneven spacing shows you they are bad. The springs hold valves on the throttle plates closed until the engine vacuum goes very high.

If your throttle is not closing every time you need to fix that. I found using grease on the springs that close the throttle really helps.

[Ron]

Pics of (bad) deceleration springs (http://dmctalk.org/showthread.php?5760-Adjusting-CO-With-A-Dwell-Meter&p=82186&viewfull=1#post82186)

[bytes311]

which by the way has anyone come up with a cup holder idea?

https://www.deloreango.com/us/drinks-holder.html

[northeast dmc]

Pics of (bad) deceleration springs (http://dmctalk.org/showthread.php?5760-Adjusting-CO-With-A-Dwell-Meter&p=82186&viewfull=1#post82186)

Thanks, the picture is a great help.

[bytes311]

Thanks, the picture is a great help.

Here's mine for what it's worth.

63800