Ok, I was pretty sure that it was normal for the pump to only pulse once in a given amount of time. What controls this, the ECM?

Its a nice day out so I think I'm going to work on relocating the coil before it gets too hot. Will rain water damage the coil in any way? After I move it I can fab up some sort of simple splash shield if I need to.

I'm also toying with the idea of putting in a small radiator fan or some such on my passenger side vent cover. I don't have a battery over there anymore so I figure it would be as good a spot as any for a fan to pull air out from. I know when I'm driving that air is pushed under the car, past the motor, and out the vents but when I'm just sitting in traffic or whatever it doesn't seem to vent too well.

One of the guys on here (I'm thinking it was Arns85GT) put fans where you are talking and had pretty good results if I remember correctly. I'm still looking for the thread where he talks about it.

Also I dug into my parts and didn't find any extra heat shields but I'll keep an eye out for some.

EDIT: Nope I was mistaken. I found Arns here and his was in a decklid Mopar Sixpack. But I assume the principle would be the same.

[This message has been edited by Silentassassin185 (edited 08-06-2010).]

No worries on the heat shields, thanks for looking though I'll just have to steal the set off of Brad's dead 2.8 or get some from the mall or something. I'm pretty sure the header wrap alone is fine, but the more the merrier, eh?

I think I have the fans article saved in my favorites somewhere but thats where I got the idea from. I think I can get away with a small aftermarket radiator fan and just wire it into my jumper point I put in after I pulled my battery out and put it up front. Well, wired in to a 2 pin connector so I can disconnect it. I still have my old mouse-chewed harness to scrounge wires and connectors from

There are two switches that can turn on the fuel pump - One is a plain oil pressure switch - thats up on the front side of the engine - its also the oil pressure sender. That one will turn on the pump whenever it senses oil pressure.

The other one is the ECM - via a relay mounted on firewall right behind the driver. The ECM/Relay is what does the prime. Thats so you dont have to crank and crank before the engine starts.

Either one can and usually both end up powering the fuel pump once the engine is running.

I should be good on all three counts then:

- new '88 style oil pressure sender
- swapped relays between AC and fuel pump on firewall behind air filter can
- remanufactured delphi ECM

So the fuel pump should be eliminated now. I'm going to move the coil behind the vapor canister to get it away from the rear manifold and crossover and EGR to keep it from heat soaking. If that doesn't fix the problem then I don't know what would.

Don’t know if this could be the answer or not, but I had a heat related problem that sounds somewhat similar on my ’91 5.0 Firebird Formula. It started running rough, and finally got to the point where it would not start at all when hot. I replaced practically everything in the ignition system, including the distributor, and got no improvement. I finally took it up to the Fiero Factory, where Jeremy diagnosed it as bad fuel injectors. Apparently one or more of the injectors would short out the ECM once they got hot. I believe you can check for this by disconnecting the injectors one at a time.

So, does this mean that it still has a problem? These cars have driven fine for many years without relocating coils and such...
More power to you if you just like tinkering.

Charlie

I haven't driven it in the heat yet so I don't know if the problem is gone. I shouldn't *have* to relocate the coil but if moving it will keep the car from stalling then so be it. I haven't had a chance to do it though, but I don't think it would take me but an hour to rewire everything and drill some new mount holes.

If I move the coil and it still dies, then I guess I'll look into swapping out the injectors for another set or something. At this point I'm just grasping at straws...

I am not saying that a coil won't act up when it gets hot as I have had that issue but if the coil is a good one it won't act up... It is just a sign that it is going bad. That thing about the injectors is interesting. When I had bad injectors it was when I received the car from my second cousin. 2 of the 6 injectors were not firing at all and another was "weak" so I did not get the opportunity to see what happens as they go bad. Good luck, hopefully the problems already been fixed...

Charlie

I'm on my second new-ish coil so its not an OEM thats dying or anything. It could also be that the aftermarket coils weren't as heat-resistant as the OEM either.

On the injectors, I would think if they were the cause of the problem that they wouldn't care what temperature it was outside. They're somewhat sheilded from heat as they're hidden under the upper intake plenum but then again any 20+ year old part can be suspect. I think Brad has a spare rail and injectors that I could grab the next time I'm over his way. At the very least I would have them as spares or send them out to be rebuilt at some point.

Anyway, I'm out of town for a couple of days with some family so I'll just fiddle with the car when I get back.

There are two fuses, and two circuits in the ECM, each running one bank of injectors. All three front injectors are wired together, and all three back are wired together. I can see how if one shorted that it would cause the engine to run rough, and also have the hot start issue however the reason they have two seperate systems is so if one fails, the other will at least keep the engine running. Since this problem is so "on-off" with the entire engine, It seems to reason that it wouldn't be a shorting injector.

^^^ Thats my thinking as well.

I do need to go through my fuse box to check that all the fuses are the correct amps for each slot. I don't suppose an incorrect fuse would do anything would it? I know at least a couple are wrong. I can't think that they would though...

Burn up your car - yes

Blow when they shouldn't - yes

Make the engine run rough - only while the car is actually buring up

I don't have any that are grossly off, just a couple of 20's where I should have 15's

So the fire they start will just be a small fire then.

That is when it starts.

update? is it fixed?

I *think* I have it fixed. It hasn't stalled on me again since I replaced the fuel pump, swapped to a GM ignition module, and relocated the coil. I did all at roughly the same time so I'm not 100% sure which is the fix, although I'm inclined to believe it was the fuel pump.

The old pump was a TRE Performance pump that was about $70 or $80 and I had read good reviews about it. However, I couldn't hear it prime despite having good fuel pressure at the rail. Just on a hunch I decided to replace it with a Delphi pump that I bought from my local NAPA for about $90 and installed it at my friend's garage with a lift. The lift made life soooo much easier as it took me all of 30 minutes to drop the tank, then maybe an hour to swish out the debris in the tank with lacquer thinner after letting it soak, and installing the new pump to the sending unit, then another 30 minutes to re-install the tank.

On the drive home I had no stalling or stuttering whatsoever as I have on other cool nights out driving. Just as a precaution I decided to go ahead and relocate the coil the next day before taking a long trip just to get it out of the heat from sitting right above the exhaust manifold and Y pipe. I have a chewed-up wiring harness that I cut the proper-sized wire from and move the coil to just behind the EVAP canister. Its a perfect fit for the factory coil mount and bolts after drilling a couple of small holes. Running the wires with scavenged loom almost makes it look OEM. I did have to buy a longer coil wire, but it was all of $5 from my local O'Reilly.

The ICM was an old one that I got with a spare distributor. It was marked GM on the sticker and it looks awfully dirty so I'm assuming its an OEM part from the '80s. I had it tested and it passed so its a good part. I don't think it was necessary to swap it in since it *is* old, but I figured it wouldn't hurt since I have spare newer modules to swap in. I have a spare $60 Borg-Warner ICM from O'Reilly and a spare $100 "Select" ICM from O'reilly in my trunk in the event that the OEM part fails. I did have a $40 Duralast ICM from Autozone that actually ended up on TwoFatGuy's car when I was following him and his ICM failed so I have plenty of practice swapping them out

So far after making the changes I've had no stalling or stuttering problems despite making several 1.5 hour long trips during the heat of the day so I think I've got it fixed. Even if moving the coil wasn't the solution for my problem, I like the idea of getting the coil away from the heat and also clearing up the pathway for the cooling tube to blow cool air over the ICM in the dizzy.