Hello! I have a 1988 2.5 Iron duke fiero. Some background information, the car used to gasp for fuel but I put a brand new fuel in it from AC DELCO and that solved it perfectly. Now a few months have gone by, and the car developed a new problem. It just randomly dies instantly, no coughing or anything. Then for a good minute or 2 you have to keep cranking it and finally it will come back to life. I have put in new plugs, a map sensor, and a fuel pump. I have checked and the relay is making noise every time you turn the key, and you can feel it switch. When it is not starting, it appears as though there is no fuel going in at all. I can take the top intake off and look down, and I see no fuel flowing in. But when it decides to run, it will run perfectly for a random amount of time, you can floor it or whatever, it does not miss a beat. I think I am going to go ahead and buy and put on another fuel filter, in the off chance that is partially plugged.

Another issue that has appeared that I do not think is related is at low rpm in third gear, the motor/transmission will start making a loud hum. It also seems to lug the motor, I can gas it for a second and it goes away for like 3 seconds, then it starts up again. It only does this at about 35-45 miles per hour, so far I have ignored it, just really annoying.

Thanks!

Cracking for 1 or more minute can quickly Kill the starter, Battery, and the big cables to the battery. GM spec is 30 sec max run time and 2-5 minute minimum cool time between tries to start.

take off air clearer cover, look into the TBI and see if you fuel spray in there.
ECM won't start fuel delivery unless sees signal from ICM/PIM. PIM could be bad, wires between two bad, or ECM is bad.

ECM can "die" from the heat generated by it and No inject feed is one symptom of this issue.
See my Cave, ECM Heat, DIS Ignition, 700 TBI, and likely other pages in those sections.

If you pull insulation and car works then ECM is still "dead" and need a new one quick. Save the prom in it to move that to new ECM.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 03-21-2020).]

Okay, I will take a look. Oh, and I am not holding the starter for minutes on end, just trying it randomly here and there.

quote Originally posted by Firezappy: Whenever the car has decided to run and start right you do see fuel spray, but when it decides to not start there is no fuel spray.

You might wish to look at This thread.

What does the tach do during this time? If the tach just sits at zero during cranking your problem is with the ignition system. The ECM fires the injector based on ignition pulses. If the ignition system has temporarily failed you will have no spark, no injector pulses and no movement on the tach.

A correctly working ignition system will show about 200 RPM during cranking.

do you have "Fuel PRESSURE" when it dies ???? just went through all that. can you HEAR the fuel pump Running when you put the key on ???

Just wanted to give everyone an update. Nothing is more annoying then unsolved mysteries after all. After making sure the fuel pressure was fine, I went and changed the coils and the ICM. This had no effect, so I moved onto the ecm. I have went ahead and bought a new one, the old one appears to be bad, I am like 95% sure. If you hit the ecm it will randomly work for a short time, vibration can make it stop as well. Thanks for all the tips everyone! It was very helpful.