Hey guys. A while back I posted a question about my '89 IROC 5.0 convert. Its 6 months later, and I still havent solved it. Summer is going fast, looking for a little advice. In the fall, I started getting a little sputtering and hesitation. It evolved into a "wont stay running" situation, and now it wont start. I replaced the TPS, the mass air flow, plugs, wires,fuel filters, fuel relays, injector regulator, and injectors. I brought it to a local mechanic who said the gas pressure was only reading 25 and dipped to 20 under acceleration. He changed the fuel pump, and it made no difference at all. At times while trying to start it, air comes out of the valve on the fuel rail when its pressed.
This is a very well cared for car, its not a beater. Its not throwing any codes, other than the Mass air flow and TPS, both were swapped out twice with new parts, just need to reset. Compression is great. No vac lines disconnected. No misfires or timing issues, it seems to be starving for fuel. The only thing I can think of is that the fuel rail is somehow clogged. This make sense to anybody? Any thoughts?? Thanks in advance.

 

Does fuel pressure rise if the return flex line in pinched off ?

 

Did you measure resistance across each injector? I had an issue with my 89 LB9 engine where one of the injectors went bad (no resistance) and it took out all of the injectors. By dumb luck, I disconnected the bad injector and the car started right up. The injection system is set up so that if one injector is bad, it stops fuel from all of the injectors. Just a thought.

 

I'd do some easy stuff first to verify / rule out what is currently happening. Buy a factory service manual for your year. Check for spark, check resistance at each fuel injector, buy a fuel pressure gauge and verify what it's doing right now. Do the return line pinch test as suggested. Sounds like your mechanic wasn't very good if they couldn't fix the problem.