Love my 89 IROC 5.0 TPI, had it for 28 years. It sat for a couple years, then drove it for a bit, then it sat again for several years. But now I have moved to a new home, and I was able to drive it the 30 minute drive from my old place to my new place. During that drive, it started to run rough when I got close to the new place, but it did not die.
But last week, I took it out for a drive, and it ran perfectly fine, through warm up and for a bit after, until I decided to step on the gas a bit. As soon as I did that, the engine completely shut off. It seemed like it just suddenly had no spark or something. It would not start at all. I pushed it to the side of the road and let it cool down for about 4 hours. When I came back, it started right up. I replicated the issue yesterday. Exactly the same thing. Runs fine during warmup and for a while after, and then when I step on the gas, it dies. I have to let it cool down before it will start again.
Does anybody have any idea what is going on? Ignition coil? Distributor? God, I hope it's not the ECM. I am assuming it is a spark issue, only because I don't think it would quit so suddenly if it was a fuel issue. It would at least chug a bit, then die.

 

Check fuel pressure, injector pulse and ohm injectors hot, and for spark. Could be icm or shorted injectors or fuel pump.

 

Test for spark, fuel pressure and injector pulse. Needs those to run and likely one failed. Purely guessing by anecdotal information, the icm in the distributor is dying from heat.
And I see way too late that Tuned already replied that Well, he knows as well as the rest of us, if not more so.

 

I replaced the ICM, but the issue persisted. I then went ahead and replaced the rotor, distributor cap and ignition coil, as these can all be susceptible to overheating, and because they are cheap to replace. The issue persists. One thing I did notice... it smells like unburned fuel (I think that's what I'm smelling) when it is warming up, and once it is warmed, I can rev it up, and I hear popping and banging from the exhaust, which I believe is unburned fuel igniting in the cats, now that they are hot. This is why I am convinced that it is an ignition issue somewhere. Could I be wrong? Could it still be a fuel issue?

 

I agree...the coils on the injectors tend to fail when they are hot.

 

What does this mean? All injectors shorting out at once when it gets hot? Or is there a common component controlling all injectors? I thought that would be the ICM, but I replaced that. I still don't think it's the fuel pump.

 

It means you need to ohm them, if they short when hot the ecms injector driver shuts off.

 

How would failed injectors account for the unburned fuel in the exhaust?

 

How do you know it’s rich not lean ?

 

If it's getting plenty of air, but not enough fuel, would you get unburned fuel coming out the exhaust? If that's possible, then yeah, I guess it could be lean. But it seems counter-intuitive to have unburned fuel if there is not enough fuel.

 

condensation or raw fuel coming out? Don’t see why is so hard to ohm the injectors. Check fuel pressure. Leaking or shorted coils or old injectors just not flowing well all are possibilities. But if you insist it’s ignition related good luck with fixing it.

 

Nice. You won't get my business talking to me like that. I never insisted anything. I just didn't get an answer to my (seemingly obvious) question. Snarky remarks are not helpful.

 

I don’t sell injectors so can’t help you anyways. Not sure why you haven’t followed others advice. I just see parts cannon getting loaded without diagnosing. Sorry if you have a issue with me just trying to assist.

 

My first, of 3 First Gen F Bodies, died when warm with no restart. It came with a Repair Shop work order, stating the problem was bad Injectors. I was unfamiliar with GM Multec injectors and replaced the coil, distributor pickup, etc., with no change.

I replaced the injectors and problem was solved. Live and learn!

Check FI Injectors resistance, Buddy!