this is my problem and I am hoping someone here can help me out.
My 1990 Iroc is misfiring and running really rough when cold, once its warmed up it runs great for a while, when its warm/hot and I shut her down I can't get it to start,it has also stalled on me and it won't start. I have to wait till it cools off in order to start it, we have pretty much covered all the electrical in the car. the next thing we thought would be the fuel injectors but I really don't want to go to that degree if that is not the problem, any ideas out there?

 

coolant temp sensor or ignition control mod.

 

done that, with no luck

 

I had a similar issue.4shops n the pontiac dealership couldnt guess what the prob was till a chevy mechanic with yrs of experience pulled the distributor and discovered that the distibutor had a crack on/in the MAIN SHAFT. I learned the hard way that 3rd gens dont have a code for a mukt up distributor.
Looks like you got nothin to lose and everything to gain. If you dont have to pay for labor. Pull it. And know for sure. Good Luck!

 

thanks I'll check that for sure,,,

 

On my 88 iroc z the exhaust pipe ran right next to my starter. So when it was hot and I shut off. I couldn't start back up for 1 hour.

Solution new starter wrapped in a heatshield

Has worked fine since

 

I had similar problems with my 1990 Iroc. Ran great but idled like crap. Worse when it was a hot day. I couldn't keep it running at a stop light. I changed the idle air control valve and it's like night and day, although the timing could use a check, it doesn't stall any more!

 

Pull the vacuum line off the fuel pressure regulator and see if there is gas in there. I had similar problems with my 91 and it was a leaky regulator. Real easy to check.

 

When you do finally figure this out.If you can find the time. Id love to know what the problem WAS for sure..lol

 

I would add that you should check your fuel pressure and see if it holds when you shut the car off. If you have an Autozone nearby it's free. It will tell you if you have a leaky injector or regulator. This is how I ended up checking my regulator.

 

Legdiian was the right one. Fuel pressure was down to 20ish psi. Regulator was good...turned out to be a weak fuel pump. I can't believe the other shops didn't pick up on this (or even myself sooner for that matter)

 

SWEET! nothing feels better than solving the problem. I think i'll check mine just because. I get my slight issues..lol. Never hurts to take a look...
If i have to im not afraid to pull the intake. Install a new FPR. its the same part for the v6 as it is the v8 . Funny the price isn't!..lol .. Im happy to hear about your success!
Genuinely Thanks