I have a '93 Camaro Z28, 5.7 LTR, 4 speed automatic, with about 96K miles on it. Recently I have been experiencing intermittent stalls. There doesn't seem to be any common factor in any occurence. Once it stalled while sitting at a stop light right after start up. Another day after driving for an hour or so, it started bucking. It all started after I fueled up one day, but mechanics seem to think that has no bearing. I just had the fuel pump changed because it was very loud and the mechanics checked the tank for particles and changed the fuel filter while they had everything out. They all seem to think it is an electrical problem but can't pin it down. They have checked plugs and wires and say it isn't the distributor. They went from front to back and tightened every wire they could find on top and underneath. I left it with them for a week and they drove it every day--nothing! One of my friends works on transmissions and hooked up the code detector under the steering column---still nothing. Hope someone can help. Thanks!

what type of pump did you install and did you change the filter at the same time? Can you see if your current fuel filter is filled with sediment? Does it stall when the car is just hot or even when it first starts? Will the car idle smoothly and just stall under acceleration?

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AC Delco fuel pump. The filter was changed at the same time. The mechanic said it was clean, as was the tank. Usually the car stalls when it is hot. But, it has stalled after only running for a couple of minutes. It actually stalled that time when I was sitting at a traffic light about two minutes from my office. However, that has only happened once. It never stalls or sputters on acceleration. Something else I have noticed when it acts up, the oil guage goes haywire. Also, sometimes when I am driving with the cruise on, it just shuts off. This, I've noticed, occurs when I'm rounding a curve. I haven't had any other serious problems with the car and this one is very intermittent. One friend suggested it might be the opti-spark. What do you think?

The early opti spark units like yours were not vented well enough. I guess it would cause misfiring. Go by a chevy dealer and ask them if that could be it. They may have a Teccnical Service Bulletin (TSB) on it and maybe even a recall on it.
David

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did it work before the new pump was installed? if so then there may be a frayed wire that is grounding out causing the pump to stop, ou car to stall and the electrical nightmare you mentioned with the oil pressure gauge to freak out.

just my 2C

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It was doing the same thing before I had the pump installed. They thought that it might have been the pump intermittently failing(it was making a high pitched whining sound). However, I talked to someone else this past week who said they were having the same problem that ended after installing new o2 sensors. The problem, on both my car and hers, was that the service engine soon light would come on and go off with the engine acting up, but a code was never stored. It was just a fluke that it happened to act up as she was leaving the mechanics shop and when she pulled back in, the light was still on. They put the tester on it and cume up with oxygen sensors. But only while the light was on and it doesn't come on every time.

I don't think I will be of much help but I have seen a problem like this on a 90 Plymouth Voyager. It would just stall when it felt like it. Sometimes months apart. Sometimes days. It ended up being the computer. It started with the fuel pump just like you said which is why I figured I would chime in. I would make sure that it is not the fuel pump and ask the mechanic to put a temporary fuel pressure gauge on it. This way you can keep an eye on it and see if the pressure all of the sudden cuts out, then seconds later the car would stall. The Dodge dealer also hooked up a small computer to the car that would record everything so when the car would stall, everything the computer did at the time was recorded. Good luck.. These things can be a big headache.

Did your mechanic bother to check the fuel pump relay and/or fuel pressure before
swapping pumps? A faulty relay will sometimes cause the symptoms you are describing and often go unchecked since they get paid more for R&Ring the pump.

Good Luck.

Yes. I asked them to check the fuel pressure before replacing. However, I didn't ask about the relay...you are the second person to mention it. Anyway, I replaced one O2 sensor (the easy one) and unplugged the other sensor and the car ran the same. I plugged it back in and drove it to my mechanic. Oddly, this time it was holding three codes: 1) O2 sensor (expected0, 2) EGR valve, I forgot the third. I know they all work together in the emissions system, but after reading up on the EGR valve, it seemed to match my experience exactly. Supposed to pick it up Tuesday....we'll see. Thanks for all of your help.