Engine missing at highway speeds

[jawn101]

I'm pretty sure that it's missing, anyway - about 10 miles into my commute to work this morning, it felt like the engine was 'stumbling' - the car would jerk around a bit and kind of shudder. It seems to idle just fine, and on my test drives this past week I haven't noticed anything like this. Just did a full valley rebuild with brand new platinum 4 plugs, HV silicone wires, cap and rotor from Hervey. Also all-new stainless fuel hoses and silicone vacuum lines.

The car started settling down when I took an off ramp and slowed down some. The drive was all done with the A/C and all accessories off. Oil pressure, temperature, voltage all looked fine if the gauges are to be trusted.

What should I look for? Is it safe to limp home (only about 15 miles) later or do I need a tow?

[David T]

I would start by going over and checking the secondary ignition circuit (spark plugs, cap. rotor, and wires) and possible vacuum leaks. Also make sure the mechanical and vacuum advance systems are working properly.
David Teitelbaum

[Michael]

You sure that its not a fuel delivery problem? Sounds a lot like a fuel pump cutting out, or a lack of flow due to a screen, kinked pickup hose, etc. Especially if it ran better at a lower engine load.

[jawn101]

You sure that its not a fuel delivery problem? Sounds a lot like a fuel pump cutting out, or a lack of flow due to a screen, kinked pickup hose, etc. Especially if it ran better at a lower engine load.

It could very well be. I just went outside and started her up again, the idle is nice and smooth (a little detonation but that's been there forever and I just haven't addressed it yet)

But, full disclosure - I was in the fuel pump access hatch in the spare wheel well last night tightening down the link from my accumulator->evaporator, which is very very near to the fuel pickups. I do not *THINK* I kinked anything because I didn't even do so much as push those hoses aside, but I guess anything is possible. I didn't disassemble or remove the pump boot or anything like that. What would I look for if I went outside at lunch and took the access hatch back off?

Here's a pic of what I saw when I removed the hatch yesterday.
2870

[WelmoedJ]

Here's a pic of what I saw when I removed the hatch yesterday.2870

If this is how your fuel pump dust cover looks like, I would take a peek at how the boot looks.
If the boot is still the original, so is your fuel pickup hose and screen.
The boot also may have developed a leak.

Is the weather hot? Than your pickup hose may collapse under load (David T. mentions this regularly and so did Dave McKeen), causing running problems.

Get rid of the old stuff and put John's new fuel pump boot with direct pickup (no collapsing, no kinking hose), boot and bracket with new clamps in your car.
You will love it.

[jawn101]

If this is how your fuel pump dust cover looks like, I would take a peek at how the boot looks.
If the boot is still the original, so is your fuel pickup hose and screen.
The boot also may have developed a leak.

Is the weather hot? Than your pickup hose may collapse under load (David T. mentions this regularly and so did Dave McKeen), causing running problems.

Get rid of the old stuff and put John's new fuel pump boot with direct pickup (no collapsing, no kinking hose), boot and bracket with new clamps in your car.
You will love it.

John's upgraded fuel pump/boot/pickup are definitely on my list. The weather isn't hot, no - it was only around 70(f) this morning on the way to work. I didn't open the pump boot because it *was* working great and I know how touchy it can be. Guess I will have to now anyway :banghead:

[1batt4u]

I was looking at your fuel sending unit, is it non-stock??

[jawn101]

I was looking at your fuel sending unit, is it non-stock??

It's actually the DMCH improved one. Came with the car. Here's a closer pic of it:

2876

[Bitsyncmaster]

If you felt the car jerk then it sounds more like fuel and not ignition like most have suggested.

How long have you owned the car? Just to determine if you just caused the problem or it never showed up before.

I would not think the pickup hose would act up at 70 deg. F air temp but that hose can fail with age or mishandling.

[DavidProehl]

[QUOTE=WelmoedJ;9348]
Is the weather hot? Than your pickup hose may collapse under load (David T. mentions this regularly and so did Dave McKeen), causing running problems.
QUOTE]

This happens to me a lot, I am running a new pickup line as well. Same symptoms where the car studders. Eventually the car kills if driven a ways after it starts happening. I remember reading on the old site about putting a spring inside the pickup line to hold it open. Does anyone know what type of spring is safe to use in there? If memory serves me I think someone used a screen door spring.

[jawn101]

If you felt the car jerk then it sounds more like fuel and not ignition like most have suggested.

How long have you owned the car? Just to determine if you just caused the problem or it never showed up before.

I would not think the pickup hose would act up at 70 deg. F air temp but that hose can fail with age or mishandling.

I have had the car since March, but never felt this before. However, like I said.. we just did a major VOD service so a lot of stuff was changed out at once, which makes it harder to pinpoint a specific action or part that may cause issues. Like I said, I did work right near the fuel pickups last night so maybe I knocked something around... I just don't know what to look for or examine to determine if there's a problem, and I don't have any parts on hand to fix anything I might find broken.

[Bitsyncmaster]

I have had the car since March, but never felt this before. However, like I said.. we just did a major VOD service so a lot of stuff was changed out at once, which makes it harder to pinpoint a specific action or part that may cause issues. Like I said, I did work right near the fuel pickups last night so maybe I knocked something around...

You may have a bad RPM relay but mostly that would kill the engine. Then after it cools it may work again for months. You can eliminate that as the cause by making a 3 pin jumper to stick into the RPM relay socket and run without the relay. The jumper is something I recommend you carry in your car anyway.

Was your fuel tank low on fuel? That would show a marginal pickup hose or marginal fuel pump. I would suggest you open the tank and inspect everything. I also recommend you carry a spare fuel pump on long trips. You never get enough warning when your fuel pump is about to die.

If you drive it home, fill the tank up full and most likely you will get it home without a tow.

[jawn101]

You may have a bad RPM relay but mostly that would kill the engine. Then after it cools it may work again for months. You can eliminate that as the cause by making a 3 pin jumper to stick into the RPM relay socket and run without the relay. The jumper is something I recommend you carry in your car anyway.

Was your fuel tank low on fuel? That would show a marginal pickup hose or marginal fuel pump. I would suggest you open the tank and inspect everything. I also recommend you carry a spare fuel pump on long trips. You never get enough warning when your fuel pump is about to die.

If you drive it home, fill the tank up full and most likely you will get it home without a tow.

The RPM relay is brand new (but old-style, not your new hotness) as well. The tank doesn't read as low, but even with that fancy new sender the gauge is of questionable accuracy anyway.

I guess I will check over the fuel pump and baffle/boot etc. The tank was cleaned out and a new sender/accumulator installed just before I bought it - and on my recent fuel filter change, the gas from the supply lines was crystal clear with no gunk. That doesn't mean there isn't a problem of course, just worth mentioning.

[jawn101]

You may have a bad RPM relay but mostly that would kill the engine. Then after it cools it may work again for months. You can eliminate that as the cause by making a 3 pin jumper to stick into the RPM relay socket and run without the relay. The jumper is something I recommend you carry in your car anyway.

Was your fuel tank low on fuel? That would show a marginal pickup hose or marginal fuel pump. I would suggest you open the tank and inspect everything. I also recommend you carry a spare fuel pump on long trips. You never get enough warning when your fuel pump is about to die.

If you drive it home, fill the tank up full and most likely you will get it home without a tow.

I filled up the tank just now and it ran fine on the way to the gas station (again, low RPM, low speeds) and only took about 5 gallons, so the gauge was correct at approx. 1/2 tank. Guess we'll see how she performs on the highway heading home. I may take surface roads most of the way and only do the highway towards the home stretch, just in case..

[Fox2506]

Starting from the beginning of the topic with my experiences:

I had a similar problem that developed after a tune-up. My car at the time would run fine, but when cruising on the highway, I could hear it start to miss when it got hot. Going uphill made it worse of course. DMCF wound up replacing the fuel distributor. It had apparently gotten clogged. Perhaps bad fuel.

On a different occasion... I once got some watery fuel at a gas station and when I put some moisture remover in, the car ran fine again almost immediately. I am sure it was this certain station that had watery fuel, because the same thing happened when I fueled up my other car. When this happened, either car would barely idle.

[sdg3205]

Yup, this has happened to me as well - even on the highway too.

Toby suggested it was a torn or collapsed pick up hose. A fill up improved the situation, but a full cool-down eliminated it.

So +1 for pick up hose.

[jawn101]

My drive home was very uneventful - if anything, the engine was spectacular. Smooth as silk. So, I guess the much lower temp combined with a newly filled tank must have inflated the hose again. Suppose another transaction with Hervey is in order, Eh? Sigh. I think I've bought that guy a boat by now :)

Thanks all for the suggestions and help.

[DeLorean03]

You'll want this kit:

http://specialtauto.com/delorean-parts/images/fuel-baffle-kit-new-2.jpg

Very straight-forward. No hoses to kink - no baffle to get all out of whack. Hasn't given me one problem in 7 years.

[jawn101]

Yeah, that's the one :) Actually, I will probably do the complete pump kit with a new boot, pump, and the baffle kit too. While I'm in there, right?

[TTait]

The baffle is already in there - with that kit you eliminate the plastic baffle (don't throw it away - some people love them and end up putting them back in). Its the round aluminum piece there. It has a small hole in one of the flat bottom pieces that goes over the stud in the bottom of the tank and you put a nut on it and its done.

For the pump you use a plastic adapter and use that to connect the filter screen directly to the bottom of the pump - no hose to collapse or kink.

I've been running one for 6 years and on my car and my wife's has had hers for four - never any problem with Herveys pickup.

That said, my pump did occasionally overheat on really hot days - the radiator kicks a lot of hat back there and it gets hot in the tank if the fuel is below half a tank. The car would start to buck or lose power. If this happens and no other cars or close I'd typically do a couple quick swerves and firm taps on the break to slosh some gas around inside the tank, and get off the road immediately and top off the tank. Hervey says his super pump is impervious to heat, so I put one of those in this evening. Hope he's right.

A few notes on that. I've seen photos showing surface corrosion on some aftermarket pumps, and I noticed that John takes a grinder to his to take off the manufacturers model number. I was worried (probably for no reason) about this so I took the pump over to my buddies at the local radiator shop. They have a white anti corrosive sealer that goes on the inside of metal fuel tanks when they refurbish them, I coated the outside of the pump with that before installing it.

His site says it installs in 30 minutes - I thought I might be able to beat that as I already have his baffle set up so it should have been pretty quick. It actually took me 65 minutes from opening the trunk to closing it again.

I can give you all a tip when installing a Hervey pump/baffle kit. You have to slide the pump up and down in the lower boot (and on some models slide the plastic adapter up and down on the intake pipe) to get the pickup filter at the bottom of the tank but not quite touching it. The first time you do it that takes a little trial and error, especially if its his standard pump that lets you vary the length of the plastic adapter on the intake as well as slide the pump up and down in the boot. The pump needs to go very low in the boot so the top half of the pump cover fits properly.

On my car that means that when you measure from the bottom of the pickup to the bottom of the outside lip on the lower fuel boot (101391) it is 7 3/4". YMMD. You can at least use that as a starting point, and you probably won't need to move it more than once with any luck.

I love the Hervey setup - the only negative thing I can say with more than 10 years of use is that when the fuel is getting very low and you take a turn hard, like a hard right turning fast from a stop at an intersection - enough to spin the wheels and kick out the rear end I mean - the car will stutter and then recover. Given how questionable the fuel sender units can be, I actually like the warning - it tells me I have less than a gallon remaining. Some people call that a problem, doesn't bother me.


By the way, to whoever mentioned that they have paid for Hervey's boat by now - I've put two cars back on the road with him... He uses your boat to cruise down to the vacation home I bought him in Belize.

[Bitsyncmaster]

Most of us have found a long drive in real hot weather the fuel pump will start to wine. You fill up the tank with cold gas and the wine will stop (for a while).

I did a lot of testing with thermocouples and found the gas returning to the tank was about 2 degree hotter than the gas leaving the tank. So your pumping the gas back to the engine and heating it up with the "overflow" returned to the tank.

If you open your fuel tank after a long drive you will be amazed how hot the gas is in there.

I did an extreme change making a cooler on the return line wrapped around my AC accumulator. I have yet to do a long hot drive but will let you know how it works out when I do.

[Canon20DFan]

Engine missing at highway speeds? Who took it?

[Canon20DFan]

I have always wondered about a fuel cooling line...

I did an extreme change making a cooler on the return line wrapped around my AC accumulator. I have yet to do a long hot drive but will let you know how it works out when I do.

[jawn101]

TTait: Yeah, I know the kit includes the baffle :) thanks though.

That was a lot of great info on the pump update process. Do you feel that the 'power pump' is worth the extra money? It's something like $60 more. Someone's gotta put gas in that boat after all :)

[jawn101]

Engine missing at highway speeds? Who took it?

Underpants gnomes... Kept muttering something about profit.. :)

[jawn101]

Most of us have found a long drive in real hot weather the fuel pump will start to wine. You fill up the tank with cold gas and the wine will stop (for a while).

I did a lot of testing with thermocouples and found the gas returning to the tank was about 2 degree hotter than the gas leaving the tank. So your pumping the gas back to the engine and heating it up with the "overflow" returned to the tank.

If you open your fuel tank after a long drive you will be amazed how hot the gas is in there.

I did an extreme change making a cooler on the return line wrapped around my AC accumulator. I have yet to do a long hot drive but will let you know how it works out when I do.

That's really interesting. What kind of flow rate is the gas returning at? How did you make the line cooler - what kind of cooling source? Just air cooling or did you rely on the accumulator hookup to be cold from compressed refrigerant? Knowing you, you probably knocked up some kind of inline Peltier-effect job with 110% thermal efficiency that also makes Julienne fries... :-D

[WelmoedJ]

Do you feel that the 'power pump' is worth the extra money? It's something like $60 more.

Unless you're aiming at a stage III, you can use the standard fuel pump he offers.
My D is a bit more pepped than standard (128 HP at the wheels) but still uses a standard pump.

Hope this helps making your decision.

[sdg3205]

Most of us have found a long drive in real hot weather the fuel pump will start to wine. You fill up the tank with cold gas and the wine will stop (for a while).

I did a lot of testing with thermocouples and found the gas returning to the tank was about 2 degree hotter than the gas leaving the tank. So your pumping the gas back to the engine and heating it up with the "overflow" returned to the tank.

If you open your fuel tank after a long drive you will be amazed how hot the gas is in there.

I did an extreme change making a cooler on the return line wrapped around my AC accumulator. I have yet to do a long hot drive but will let you know how it works out when I do.

We've been over this before, but check this out (http://brightonracingproducts.com/store/index.php?main_page=product_info&products_id=10).

The fan kicks on at 180 degrees. Do you recall getting temperatures that hot, Dave? Pretty cool little rad you could wire in if you could fit it anywhere!

[jawn101]

Unless you're aiming at a stage III, you can use the standard fuel pump he offers.
My D is a bit more pepped than standard (128 HP at the wheels) but still uses a standard pump.

Hope this helps making your decision.

Thanks! That does help, my D is mostly stock and will likely remain that way.

[David T]

Adding a fuel cooler could be a good idea. Problem is where to do it. You could do an air cooler but you aren't gaining much when it is 100 degrees. My idea is to wrap a line around the A/C accumulator but you will be reducing the output inside the cabin. Might not be enough to matter. BTW my fuel pump doesn't wine, it whines! Only when it is really hot and the fuel level is low, Putting a spring inside the pick-up hose did help a lot though.
David Teitelbaum

[content22207]

The receiver/dryer (so called "accumulator") is located outside the passenger compartment, and it is located after the evaporator (it does not accumulate a single drop of liquid freon, no matter what people call it) -- wrapping a fuel line around it would have absolutely no effect on passenger compartment cooling whatsoever.

Bill Robertson
#5939

[DeLorean03]

The baffle is already in there...

I love the Hervey setup - the only negative thing I can say with more than 10 years of use is that when the fuel is getting very low and you take a turn hard, like a hard right turning fast from a stop at an intersection - enough to spin the wheels and kick out the rear end I mean - the car will stutter and then recover. Given how questionable the fuel sender units can be, I actually like the warning - it tells me I have less than a gallon remaining. Some people call that a problem, doesn't bother me.


That was a VERY good write-up. It's been so long since I installed the baffle kit, I had forgotten you had to "guesstimate" where to install the pump in the boot to keep the filter from resting on the bottom of the tank. And yes, I agree with the "be careful going too fast around a corner" bit with low gas. I noted as well that if I try to "floor the accelerator" from a dead stop, my car would "miss" a little before picking the fuel up into the pump. Not that that is a bad thing, just a warning for "low gas."

On another note, get John's power pump. I used to buy the high volume replacement pump at $89 a pop, and I think I went through 2 of them in under 6 years. I have had the power pump now since about 2008, and I truly don't think I have ever heard the power pump whine. Of course, I am the kind of guy that when my fuel gauge reads even 1/2 full, it's time to fill up.

[content22207]

John's baffle is totally open on the bottom -- it's baffling abilities are compromised accordingly. A solid bottom baffle will hold fuel even around hard corners.

Bill Robertson
#5939

[Bitsyncmaster]

I like wine much better then whine:o

I don't think I lost much if any cabin cooling since I still get about 44 deg out the center vent even when it's really hot outside.

[Bitsyncmaster]

We've been over this before, but check this out (http://brightonracingproducts.com/store/index.php?main_page=product_info&products_id=10).

The fan kicks on at 180 degrees. Do you recall getting temperatures that hot, Dave? Pretty cool little rad you could wire in if you could fit it anywhere!

That's a pretty nice product but finding a place to mount it is hard. I considered that type but even though it was work installing the accumulator cooler it was less work than putting in an air cooled one. My pump would start to buzz when the gas in the tank got over 120 deg. F.

[DeLorean03]

That's a pretty nice product but finding a place to mount it is hard. I considered that type but even though it was work installing the accumulator cooler it was less work than putting in an air cooled one. My pump would start to buzz when the gas in the tank got over 120 deg. F.

I risk going :offtopic2: here but.....

I have something very similar to that on my auto transmission to help keep the auto trans fluid cool. We devised a mount by making two aluminum brackets to mount the small radiator to, and then the aluminum brackets mounted to the frame. Mine is mounted where John's "hot air dam" goes, but it's not RIGHT behind the radiator and fans - or there'd basically be no point to it as constant hot air would be hitting this smaller radiator and basically neutralizing the cooling effect on the auto trans fluid.

Bottom line, well worth the time and money put into it.

[content22207]

I like wine much better then whine:o

I don't think I lost much if any cabin cooling since I still get about 44 deg out the center vent even when it's really hot outside.

That's what I pointed out: the receiver/dryer comes *AFTER* the evaporator -- it has absolutely no effect on cabin cooling.

The thing is located *OUTSIDE* the passenger compartment, for crying out loud. It is cold is because the freon is still gaseous as it passes through it (the low side hose in the engine compartment is cold too). Freon will continue to absorb heat as long as it is a gas. It doesn't release heat until it is forced back into a liquid under pressure.

Bill Robertson
#5939

[David T]

Adding more heat to the A/C (anywhere in the system) is just that more heat (energy) the A/C system has to transfer and exchange to the outside air. Getting back to the original question,
What kind of spark plugs do you have?
I ask because for a while the Bosch iridium plugs were being used as upgrade replacements and it was discovered the porcelain seals would leak allowing combustion pressure to escape. It caused the motor to develop a miss. Those plugs were supposed to last 100,000 miles and were expensive!
The reason the A/C dryer/receiver is called an accumulator is because it is where the refrigerant can expand and contract allowing a variation in the volume to compensate for the varying system pressure in relation to the ambient temperature. The valving in a Delorean is VERY unsophisticated especially in comparison to other contemporary vehicles. For instance, using cycling to prevent evaporator freeze-up is really crude way to do it. We similarities with the brake system. No proportioning valving, no pressure warnings, no residual pressure valve, no separate reservoirs for front and rear systems, no cross-feeds. Very simple for that era. (Don't confuse the accumulator in the A/C with the accumulator in the fuel system).
David Teitelbaum

[82DMC12]

I am getting into this late but I can't help but notice you used Hervey's ignition cap. I know of two specific cases where his cap does NOT fit exactly like the OEM cap which causes all sorts of ignition problems. I would consider the cap suspect since this happened after your did a tune-up, even though you are now on a fuel-delivery crusade.

[jawn101]

David T - I am using the Bosch Platinum 4's
82DMC12 - I didn't notice any fit issues with the distributor cap but it might be worth checking... the problem has gone away at this time though, it only happened that one morning - so if it was something more static like plugs or a cap, I would think it would have continued.

I am still having that odd issue with my flickering battery light (cross post: http://dmctalk.org/showthread.php?858-Battery-light-flickering) - could that be related or is it just a coincidence?

[Bitsyncmaster]

The reason the A/C dryer/receiver is called an accumulator is because it is where the refrigerant can expand and contract allowing a variation in the volume to compensate for the varying system pressure in relation to the ambient temperature. The valving in a Delorean is VERY unsophisticated especially in comparison to other contemporary vehicles. For instance, using cycling to prevent evaporator freeze-up is really crude way to do it. We similarities with the brake system. No proportioning valving, no pressure warnings, no residual pressure valve, no separate reservoirs for front and rear systems, no cross-feeds. Very simple for that era. (Don't confuse the accumulator in the A/C with the accumulator in the fuel system).
David Teitelbaum

Actually the AC accumulator is to capture any liquid freon that comes out of the evaporator so it won't damage the compressor. Like you said the orifice system is very simple and does not change all the liquid back to gas in the evaporator. It has the combined function of also drying the gas.

Hence that is why the accumulator gets cold. The liquid changes to a gas.

edit:
You would not want to insulate the accumulator because that would defeat it's function and damage the compressor.

[David T]

Correction on the plugs they WERE the platinum, not iridium. Pull the plugs and examine the porcelain. You will notice a discoloration above the shell if they are leaking. I would just replace them as long as you are removing them, if they haven't failed yet they probably will. They are not really necessary unless you are putting a LOT of miles on the car and most of us do not. Most of us do not need spark plugs that last 100,000 miles in our Deloreans! If the missing problem comes and goes I would suspect a vacuum leak. I do not think (but it is possible) the flickering battery light and the miss are related. If they were then they would both come and go together.
David Teitelbaum

[jawn101]

Correction on the plugs they WERE the platinum, not iridium. Pull the plugs and examine the porcelain. You will notice a discoloration above the shell if they are leaking. I would just replace them as long as you are removing them, if they haven't failed yet they probably will. They are not really necessary unless you are putting a LOT of miles on the car and most of us do not. Most of us do not need spark plugs that last 100,000 miles in our Deloreans! If the missing problem comes and goes I would suspect a vacuum leak. I do not think (but it is possible) the flickering battery light and the miss are related. If they were then they would both come and go together.
David Teitelbaum

The plugs are brand new as of three weekends ago and they have less than 50 miles on them, so even if they were having issues they probably wouldn't show it yet.

[DeLorean03]

You know - I can't help but notice you have engine misfiring at highway speeds and battery light flickering problems at the same time. These two things have got to be interconnected.....

[82DMC12]

Basically what David is trying to say is there is a reason the DMCH-related dealers and PJ Grady don't sell iridium or +4's. They are a waste of money and have their own set of problems. Just go with the standard Bosch copper-tip. In the decade plus that I have owned my D I've seen tons of owners buy +4's only to switch back to coppers because they had problems with them.

Andy

[jawn101]

D03 - I think they were just coincidental occurances brought on by me stretching the car's legs for the first time in a long while. The 'missing' symptom is gone now - I think it was just a fuel pickup hose as many folks have suggested. But I will definitely take David T and Andy's suggestions to heart re: the plugs. They were just what came with Hervey's tune-up kit, so I put them in. What I pulled out were nice, relatively clean Bosch platinum plugs (not the +4 models)

[DeLorean03]

Yeah, discard the 4+ tips. Junk for the DeLorean. Get good ol' regular Bosch copper plugs.

[sdg3205]

Is there a specific part number for this screen door spring I keep hearing about? It would be nice to pick one up at a hardware store instead of shipping one hose across the country!

[DavidProehl]

Is there a specific part number for this screen door spring I keep hearing about? It would be nice to pick one up at a hardware store instead of shipping one hose across the country!

I just did this 2 weekends ago. I followed this how to: http://www.dmcnews.com/Techsection/fuelhose.htm

It is a standard spring, I bought it at home depot and used a Dremel to cut it to the proper length. It is REALLY hard to push the spring through the hose, even with using dish soap as lube. I think I spent an hour slowly working it through. I had to use the part of the spring I cut off to push the section I was using into the right position once it all got through. I've only driven to and from the gas station since I did the mod, so I can't speak yet to how well it works. Ask me again in November and I'll let you know if I'm having issues.

My primary concern is that the spring will force the hose too straight and will cause kinking at the connection to the fuel pump when hot (spring ends just before the elbow to the pump). Without the spring the hose had a nice curve to it that positioned it perfectly where it needed to rest.

[sdg3205]

I just did this 2 weekends ago. I followed this how to: http://www.dmcnews.com/Techsection/fuelhose.htm

It is a standard spring, I bought it at home depot and used a Dremel to cut it to the proper length. It is REALLY hard to push the spring through the hose, even with using dish soap as lube. I think I spent an hour slowly working it through. I had to use the part of the spring I cut off to push the section I was using into the right position once it all got through. I've only driven to and from the gas station since I did the mod, so I can't speak yet to how well it works. Ask me again in November and I'll let you know if I'm having issues.

My primary concern is that the spring will force the hose too straight and will cause kinking at the connection to the fuel pump when hot (spring ends just before the elbow to the pump). Without the spring the hose had a nice curve to it that positioned it perfectly where it needed to rest.


I had no luck finding this spring at home depot today.

Anything else more specific about it that might help me find it?

[Bitsyncmaster]

I had no luck finding this spring at home depot today.

Anything else more specific about it that might help me find it?

It could be any spring that is about the ID of the hose or smaller. You stretch it out to make it more flexible. Make sure you bend the ends and or file off any sharp edges so it won't puncture the hose. I had one installed but removed it when a installed a new hose.

[Jim D]

I am new to the Delorean world and since several folks have discussed changing plug wires and distributor caps here, I have a question. Is there an easy way to get to the distributor cap? I am assuming that the fuel distributor and air intake module have to be removed to get into the distributor area. True? If so where is the best place to remove this assembly, at the square intake joints or the round tube assembly? Any advice on doing this? I too have a miss and a very rich mixture so I am guessing a ignition issue with the cap or wires.

[Bitsyncmaster]

I am new to the Delorean world and since several folks have discussed changing plug wires and distributor caps here, I have a question. Is there an easy way to get to the distributor cap? I am assuming that the fuel distributor and air intake module have to be removed to get into the distributor area. True? If so where is the best place to remove this assembly, at the square intake joints or the round tube assembly? Any advice on doing this? I too have a miss and a very rich mixture so I am guessing a ignition issue with the cap or wires.

A miss may be caused by a rich mixture fouling a plug. Your cap and wires will not cause a rich mixture. Is your FV (frequency valve) buzzing when the engine is running?

Not that you should not remove the intake and clean the valley but if your just trying to get the car running good, better to wait till you get the engine running with no problems. You may cause another problem removing the intake and then finding that new problem would be more work.

[Jim D]

The frequency valve and everything associated with the fuel system has either been replaced or checked out by John H. I thought the missing and the strong fuel smell of the exhaust could be due to a plug not firing, The wires are old and the car was sitting a long time before I came along. I just thought there must be a easy way to get to the distributor. I also need to check for vacuum leaks but that looks to be a pain to get to also.

[DMCTek]

To answer your question it does not really matter where you unhook the "W" pipe. The square end uses a paper gasket to seal and the round end uses a o-ring seal. The hardest part about removing just the metering section is replacing the idle air tube. As mentioned you may want to remove the entire intake and clean the valley (top on the short block). This area is known to collect coolant/debris and rot the block.

That being said your issue is more likely fuel related as Dave mentioned.

Can you give us a little more to go on? When did this appear? How long had the car sat prior to the misfire showing up? Is your condition at idle, under load or both?

[DMCTek]

Has the CO been properly adjusted?

A tune up is good idea if you don't know the age of the plugs and wires. That way we can focus on fuel system if the problem still exists.

[Jim D]

Thanks for the info. The car's last inspection sticker was 1987 and it has around 16,500 miles on it. The PO said he started it up several times a year and everything worked on it, (not quite!) I found many electrical issues which I have corrected. I cleaned out the gas tank (it was not in bad shape), bought the John H. FI rebuild kit, including new SS fuel lines, fuel pump, fuel filter, new accumulator and sent him the injectors, and anything hooked to the fuel lines for inspection. I feel that the fuel system is functioning properly. It starts well but has a strong smell of unburnt fuel and the miss which continues as I accelerate. I just figured that perhaps the plug wires may be breaking down or I may have a problem at the distributor cap, but with the FI/air intake mounting, I cant even see the distributor.
I was trying to figure out a easy way to remove the air induction system so I could get to the "valley" check for vacuum leaks and change the distributor cap and wires. Plugs are new.

[Bitsyncmaster]

When I did my plug wires I had the intake removed so not sure if you can do it with everything still bolted down.

Like you said, electrical issues are very common. That is why I asked if you hear the FV buzzing. If not, it may just be a bad connection.

[DMCTek]

Thanks for the info. The car's last inspection sticker was 1987 and it has around 16,500 miles on it. The PO said he started it up several times a year and everything worked on it, (not quite!) I found many electrical issues which I have corrected. I cleaned out the gas tank (it was not in bad shape), bought the John H. FI rebuild kit, including new SS fuel lines, fuel pump, fuel filter, new accumulator and sent him the injectors, and anything hooked to the fuel lines for inspection. I feel that the fuel system is functioning properly. It starts well but has a strong smell of unburnt fuel and the miss which continues as I accelerate. I just figured that perhaps the plug wires may be breaking down or I may have a problem at the distributor cap, but with the FI/air intake mounting, I cant even see the distributor.
I was trying to figure out a easy way to remove the air induction system so I could get to the "valley" check for vacuum leaks and change the distributor cap and wires. Plugs are new.

Was the Fuel Distributor checked out also?

[Jim D]

The fuel distributor was replaced with a rebuilt one.

[Rich]

Is there an easy way to get to the distributor cap? I am assuming that the fuel distributor and air intake module have to be removed to get into the distributor area. True?.....I too have a miss and a very rich mixture so I am guessing a ignition issue with the cap or wires....It starts well but has a strong smell of unburnt fuel and the miss which continues as I accelerate. I just figured that perhaps the plug wires may be breaking down or I may have a problem at the distributor cap, but with the FI/air intake mounting, I cant even see the distributor.

The distributor cap can be seen most clearly from the left side ahead of the intake manifold and beneath the fuel distributor. Before you start replacing spark plug wires or the cap yourself -

Find a mechanic who can diagnose spark strength at or near the plug. Get all 6 wires checked. From there you can proceed upstream into the spark delivery or downstream to the plugs. A regular misfire, as if one cylinder is dead, can be due to a wire, the cap, a plug or an injector as far as top-end work goes.

By the way, how do you know that you have a "very rich mixture"? If your engine is misfiring then the unburnt fuel will make the exhaust smell like the engine is running rich, at least after the cat. converter gets going. Try to fix the misfire soon - catalytic converters don't like a steady diet of unburnt fuel.

[thirdmanj]

I haven't read every post on this thread, so, at the risk of sounding like a complete idiot, have you checked all of your spark plugs insulators for cracks? I had a similar issue a while back and that turned out to be the problem. Of course my missing was very subtle. But hey, it's worth a shot.

[Jim D]

The plugs are new so I believe the ceramic insulators are good. Can the cap and plug wires be replaced without removing the fuel/air distribution system?
I do believe the fuel smell is due to a misfire, that is why I was going to replace the cap and plug wires.