I have a 94 Camaro Z/28.
Ok, so here's my dilemma:
My car will run for a little bit, then all of the sudden slightly sputter and die. It generally has to sit for a while before it will start back up, and when it does, it will only run for so long before it dies again. Heres what I've done to try and find/fix the problem:
Replaced fuel pump with AC Delco
Replaced fuel pump relay
Replaced optispark
Replaced battery

I'm going crazy trying to get this car fixed. If anyone has had the same or similar issue or knows how to fix, please help!

 

alternator

 

is it throwing any codes??? and i doubt the alt if it just starts back up with out a jump i would say the comp doesnt like something or is malfunctioning itself

 

The alt was rebuilt about 6000 miles ago so I dont think its that. Today is when I replaced the fuel pump and it ran great for about an hour. Just as I jumped in to take off it died. So it ran longer than it has in a long time after replacing the pump. I havent checked codes as I dont have the equipment to do so. I'm guessing that should be my next investment.

 

Would you say that the car runs only until the thermostat opens? (i.e. gets to temperature).
Im not sure but I would have tried using a different ECM first. Maybe you can get one cheap at a junkyard and try that.
Something appears to be changing after running for some time that is causing the engine control to freak out and shut down.
I hope this helps.
good luck

jim

 

You did not mention replacing the fuel filter, it should have been changed before going after the fuel pump.

 

Is it getting to operating temperature? I know some people have had problems with heat soak in the coil. Generally they replace them and space the bracket out with washers and it tends to fix the problem.

 

It runs fine up to op temp and beyond. I have manual fans connected so thats not the issue.

I forgot to add those to the list of replacements. Ive replaced the fuel filter as well as the ICM along with spacing it from the head, and the Ignition Coil. ECM is the only other thing I can think of. I've been looking for a cable to hook up to my laptop as I found some software for reading codes withouth spending 200+.

 

Ok so I picked up an ECM from a 95 Caprice out at the local junk yard. Car runs fine now, BUT it wont shift into 2nd, 3rd, 5th, 6th or R when the car is running. It will if its off though. I disconnected the battery when I installed the ECM to reset. Any ideas?

 

sorry that was my only reasonable guess. The only other thing i could think of is your getting bad gas or water in your tank. but im going to guess you went through a few tanks of gas. sorry i cant help more.