I've read and searched so many great threads but haven't ran across anything that is pinpointing to the problem I'm having. 92' 305TPI, 5 speed. Trans am was purchased from a lady who had it sitting in her garage since 2013. Ran long enough to limp it on a trailer. When I brought it home I replaced fuel, fuel filter and drove it around. It ran awesome for about 2 days, no issues whatsoever. Then it began to die at every red light or stop sign, it would fire back up but I just got to the point where I would feather the gas to keep it running. Fast forward about a week, now its in the garage and I don't dare drive it.

It takes a lot of gas pedal play to get it started and once fired up it dies immediately if you take your foot off the pedal. However if you keep your foot on the gas it will stay running, just super rough, It sounds like its missing. Running really rich, black smoke coming out the tailpipes and I mean its thick eye burning smoke. It'll do that for about the first 5-6 starts, then it wont start at all. On the back of ICM there are two quick connects one is a 2 prong that comes from the coil, another is a 4 prong that comes from the harness. If I unhook the 4 prong it will start up again and run rough, it does that for about 2-3 starts then it wont start at all and backfires. Once I reconnect the 4 prong connector it'll fire right up and run like it did brand new for about 5 minutes then it will die, and if you restart it, its the rough running, black smoke, feathering the gas procedure all over again. I've replaced the ICM, IAC, checked the TPS (its good), new cap, rotor, plugs, wires, air filter, fuel filter. Sorry for the long read I'm just hoping someone knows exactly what the issue is. It has something to do with that ICM and the 4 prong connection wherever it goes. Thank you for any help

 

Don’t see how the ecm can fire the injectors without a reference pulse. Check for fuel pressure bleed off. It might be flooding and your cutting of even more excess fuel.

 

 

Yup, that’s the reference and timing control to the ecm.

 

Ok what is the best way to do that? Thank you

 

With a fuel pressure tester. Koeo to prime and watch pressure rise. Then watch to see if it falls quickly. Typically if it’s not going back to the tank should hold up to 10 min. The test port is on the passenger side rear of the rail.

 

Sounds like the FPR is leaking fuel into the plenum via the vacuum line. IOW, the FPR diaphragm is shot.

RBob.