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1997 Camaro Z28 - intermittant non start when engine is warmed up

I have a 1997 Camaro Z28 with 37,000 miles. A year ago it developed a problem of not starting after driving and being warmed up. The best description is when running errands, after the 2nd or 3rd stop, it will not start. If I let it sit for a couple of hours, then it will finally start, but I have to pump the accelerator to get it to start. If it sits overnight, it starts like a brand new car. When the problem happens, the starter is engaging and the engine is cranking. I have had a mechanic spend hours trying to diagnose this and has had no luck, partially due to the intermittancy of the problem. The car is an automatic, not a six speed.

Pumping the accelerator shouldn’t have any effect on a fuel injection car. This is the last of the LT1 cars with the OptiSpark distributor, notorious for problems similar to what you describe. No start when hot, long crank times, struggle to fire, all these problems have been described for this ignition when failing. Heat and moisture hurt these things and there is a lot of that in the front of the engine. Many with no error codes set.

Apparently people have found that pressure washing the engine does harm to the OptiSpark. If you have done this lately, that may help pinpoint it.

Replacements are pricey - $350-$600. Aip Electronics has what they say is an upgraded unit new for $100. Good Luck and let us know what you find.

The problem might be caused by a crankshaft position sensor failing when it gets hot.

If the computer loses the signal from this sensor the computer see’s no reason to operate the ignition and fuel systems.

You can check for a bad crank sensor by starting the engine when it’s cold. Then take a hair drier/heat gun and point it at the sensor. If the engine suddenly shuts off you know it’s the crank sensor.


97 Camera w/only 37K miles? Cool. Sounds like a fun drive.

Most likely this is either a no-spark problem, or a no-fuel problem. I presume the CEL is not on, and you’ve already checked the ECM’s diagnostic trouble codes and nothing is active or pending. Not sure if this is possible on your car, but on some cars you can insert a spark-detector gadget in-line with a spark plug wire to see if a spark is occurring. That’s how I would start. Most auto parts stores sell those gadgets, and tool stores having an auto-tools section often sell them too.

Mustangman, Tester and GeorgeSanJose

Thank you for your responeses. I was holding off making another appointment with my mechanic until I received respones.

I will keep you posted as to my success.

Thanks again,

As a follow up to your suggestions my mechanic finally determined what was actually wrong and my worst fears were confirmend. Dying/dead fuel pump. Many hundreds of $ later, it’s running like new again. Thanks again for all of the suggestions, it helped me through the process of elimination to determine the problem.

Thanks for posting the follow-up. There’s been a few other posters who’ve had the same thing, a fuel pump can become intermittent when it gets hot. Glad you got your car back on the road and working well again.

It’s odd that a pump with only 37k miles on it would die; even intermittently. Maybe there was an underlying reason for it going south; fuel contamination, partially clogged filter, etc.

Yes, the pump change on those cars is kind of a pain in the neck. Exhaust off, rear axle dropped, etc.