94 stumbles and dies once warm.

[TexasRebel]

If it was me I’d check fuel pressure. Tbi don’t have a schrader valve so you’d have to pull the line and put the adapter in there. But in my opinion that’s where I would check first. I know you said pump is new but that doesn’t mean a thing. I’ve gotten defective parts plenty of times.

I'll see if I can get my hands on a tester soon. On a budget now so gotta pick and choose what I do at this point. I have a spare brand new Delphi pump I bought before I knew the whole sending unit was bad. Worst case I'll swap it in.

 

[TexasRebel]

I had a 94 with 5.7 TBI that was doing the same thing. I replaced plugs, wires, rotor, cap, and icm. None of it helped. Then I happened to read, on some obscure and now forgotten corner of the web, that an overheating icm can cause this exact issue (runs fine when you first start it up, but bucks and dies when you give it throttle at normal operating temps). So I went to BestBuy and bought a tube of thermal paste, which is used to dissipate heat between components of high end computers. I removed my icm, coated the back side of it with the thermal paste, and reinstalled. I never had another issue again.

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I have a spare tube or two sitting around in a drawer somewhere from previous pc builds. I'll have to see if I can find them. Not a best buy close to me so worst case I'll just prime ship it to me from Amazon. I covered the plate pretty good when I replaced it, but wouldn't be surprised if the quality of the paste that comes with the icm is garbage at actually transferring the heat away from the module.

 

[TexasRebel]

I second that, unfortunately for OP, he has replaced many thing looking for the right thing. Hard to say. And 100% new parts dont mean they are good, and even if they test out good, they still might not work. Had that happen to me on my daughters tahoe, and the knock sensors.

@TexasRebel ......

I suppose this is a long shot.....but if it seems to stumble when warm, I wonder if it is a vacuum leak. Old school way of checking this was start the engine, spray carb cleaner anywhere air could get in the engine other than the TB. Its seems it would fit your issue. Or perhaps a clogged cat. Hope you figure it out.

Yeah. Sucks I've spent this much trying to diag the issue, but at the same time I'm sure most of this stuff needed replaced anyways. I'm going to see about getting a fuel pressure tester soon.

I've been checking constantly for vacuum leaks and haven't found any. Already replaced most of the vacuum line before I started the project because it was brittle and cracking up. Impossible for the cat to be clogged at this point. We hollowed it out about 12 or 13 years ago because it had broke apart and lodged the filter media sideways.

 

[Sabinoerc]

If it was me I’d check fuel pressure. Tbi don’t have a schrader valve so you’d have to pull the line and put the adapter in there.

agree, starting with known good fuel pressure is first. After fuel filter and before TBI. If you release the clamps on line going up to TBI it makes enough space to get the adapter in.

 

[Schurkey]

Doesn't matter how new or wonderful the fuel pump is...


...if the power supply to it, or the ground connection, is defective.

What is the voltage near the fuel pump, with the pump running?

 

[Sabinoerc]

Yeah, I jumped to conclusion that fuel pressure was good but if something was still bad after a new pump you’d be chasing your tail. Good to verify. Maybe autozone has loaner tools but memory is the gage/adapter isn’t too expensive.

along those lines, another basic is verifying all the grounds are good, especially the one on CTS which I think is the ECM ground?

 

[cantseeme95]

Have you tried a new Temp sensor? The one at the thermostat housing, not the one on the driver side of block. I had a similar issue with a 94 Blazer. Temp sensor took care of it. Good luck.

 

[1997]

Just changed o2 sensor. Problem still persists. I can only idle it up if I do it very slowly. As in one toe just barely easing into the pedal.

AC delco?

 

[Rod_Pow]

Yeah. Sucks I've spent this much trying to diag the issue, but at the same time I'm sure most of this stuff needed replaced anyways. I'm going to see about getting a fuel pressure tester soon.

I've been checking constantly for vacuum leaks and haven't found any. Already replaced most of the vacuum line before I started the project because it was brittle and cracking up. Impossible for the cat to be clogged at this point. We hollowed it out about 12 or 13 years ago because it had broke apart and lodged the filter media sideways.

Any updates on your issue?

 

[udidwht]

EGR