Missing

[MrYomomoto]

Hello all I have a crazy one for you.

My 95 C with 5.7 TBI is having some problems. The problem started slowly and has become worse over time with the truck stalling and lacking power now. I don't know what else to do and can't seem to find anything wrong with the truck other than it does not run correctly!

Here are the specifics:

No codes from the computer.
EGR looks and moves good.
MAP tests ok
Cap, rotor, plugs, rotor all new
Coil tests ok
pick up coils tests ok
Fuel pump does pump fuel but I have not done a pressure test.
fuel filter new
intake gasket new (was told to change this by a friend.)
Rebuilt TBI and cleaned injectors.
Timing is TDC when disconnected from the computer.

Any help you can give me would be great as I have been fighting this problem for a few months and can't afford to take it in for work.

Thanks!

[Riche]

try a compression test

[horse482]

The egr valve could look good but be opening early. Check for side to side play in the distributor shaft, my truck was doing the same thing and the shaft was whore out. Replaced the distributor with a gm new and it fixed the problem.

[67malibu]

Does it miss all the time or only when the engine is up to temperature? Does it miss at idle, under load (worse when pulling a hill with the converter locked up) or all the time? Coils (particularly the pickup coil) can be burning out but test good when cold. Also you didn't list the plug wires as being replaced (could easily be causing this.) One thing to try is to see if it's one or two cylinders not firing consistently or it's random. Use a induction timing light or loosen the plugs at the distributor and use a well insulated pair of pliers and/or some thick gloves and take one wire off at a time. Knowing if it's one or two cylinders or if it's random will help the diagnosis alot.

[MrYomomoto]

First, thanks a ton for the quick response

Okay a few answers to the posts.

Plug wires were replaced.
The problems seemed to start slowly and progressed over time until now the truck is not running correctly.
Truck will idle fine when cold the dies as it warms up.
If the coolant temp sensor is unpluged truck will idle again.
Collant temp sensor was replaced due to me breaking it on accident when going to test it.

Truck lacks power and when trying to get to speed has to be "pumped."
I will check to see if some of the cylinders are not firing.

I did take one plug out to find TDC when reinstering the distributor and it seems to show a rich mixture.

When you say check side to side movement do you mean rotational or left and right? Should there be no movement at all or is some allowable?

Thanks again.

[MrYomomoto]

Oh, I forgot to add. While sitting in park I wanted to see what the truck would do while not under a load.

Got it to about 3000RPM and wanted to see if it would run okay and it did. I kept it here for about 30 - 45 seconds and it ran smooth. As soon as I got off the gas it died.

[MrYomomoto]

Just wanted to thank all of you for your help....

It turned out to be the fuel pump. I guess it just wasn't producing enough pressure.

Thanks again