I bought a 91 z28 that was sitting on the side of someone's house for at least a year. They parked it because it would overheat, I brought it home via trailer, and had to start fixing all the things they took apart. I put on a whole new exhaust , manifolds and all. New temp sensor, radiator cap, re hooked up all the vacuum lines, and the heater lines. I put on a new cap and rotor new plugs, and it was running good, no overheating. After a few minutes of running it shut off and would not restart, just kept turning over. I changed the alternator because it went bad, and changed the starter, it's getting spark at the coil, fuel pressure is at 40-45 at the rails. I was messing with it today, wouldn't start just kept turning over, then it fired up, ran great. It started idling up and down a little, so I turned it off and installed a new air idle sensor I had already to see if it would help, and of course it won't start again,just keeps turning over. I put itin neutral and no difference. Any suggestions? It's a 305 tpi

 

Puled the engine codes to see if anything showing ?

https://www.thirdgen.org/forums/tech...s-dumbies.html

 

No engine codes showing,

 

some one help us i have the same problem with a 89 2.8

 

I'm chasing a similar problem, but it's only after the car sits over night, cranks but won't start. After unplugging and reattaching some connectors like the IAC or coil feed wires, it will crank right up. I've pretty much eliminated everything except some possible bad wiring/connection somewhere or a buggy ECM, but I'm still looking.
Here's the trouble shooting from the manual. Maybe this will help you.

 

One more page.

 

ground the fire wall , intake and coil. and any place u can put a strap!
every85-90 chevy i ever owned has had this problem , u crank and crank nothing , pull a plug wire use a screwdriver ground it out on the exaust , put it back if it starts , its proably a bad ground to the coil.

 

Yeah, was was thinking a bad ground might be a possibility. I'm thinking about running another ground strap to the engine to see if it helps. I've been cleaning and reseating all the chassis grounds I can find and get to in the engine bay, hasn't made any difference yet. I need to check the big braided ground strap connection at the back of the passengers side cylinder head, but it's a real S.O.B to get to with a wrench.

 

So you are missing either fuel or spark ( or both if unlucky )
Spark at the coil does not mean spark in the cylinder. Pressure at the rail does not mean fuel in the cylinder

Pull a spark plug out to narrow down the problem
Wet plug ; no /low spark
Dry plug ; no fuel

Only then can you start to identify what the actual problem is

 

It's fixed now, the problem was the fuel injectors. I replaced them with Bosch rebuilds from South Bay fuel injectors 18-20 stock replacements, fires up and runs great. Thanks for all the help.