well i finished my header install and drove it around open headers for two days and on the third day the car wouldnt start. next day car started. shut it off at the gas station when i came back.....nothing. towed it home. started the next day.... so on and so on. well i'm pretty sure its the fuel pump because when i push the fuel purge valve thing no fuel comes out(when it wont start) and i dont hear it when i turn the key forward. but it starts and run when it wants to..... does anything shut off the fuel pump? or is it just going bad? groung cable? anything i can check would help.its a 96 m6 if it matters, sometimes it will start up and shut off right after that the rest of the exhaust is on now if that helps any. thanks in advanced -brett

 

I would get a fuel pressure gauge and hook it up to the rail and see what pressure you are getting when it does prime and pump. If it doesn't prime sometimes, it might be a wiring issue, if it primes, but fuel pressure is erratic or zero, you probably have a bad fuel pump or a bad fuel pressure regulator.
If for some reason it turns out not to be a fuel issue, I would suspect the ICM.

 

thanks for the input anyone else?

 

I had the exact same symptoms when my fuel pump went out. You can do the electrical testing if you want to, but chances are it's the pump.

 

how do you test the electrical stuff? anyone else have some ideas?

 

Taken from Harlan Hynes' LT1 No Start Diagnostic at mainstreamtopics.com

Fuel system electrical diagnostics

First we need to get at the fuel pump relay. Here is a picture of it http://shbox.com/1/fuel_pump_relay.jpg *note 93-95 and 96-97 systems are slightly different*.

With your test light at the relay test for ground on the black/white wire. Do you have a ground?

Yes, continue to next step
no, repair ground wire.

Next with your test light and the key in the Key on engine off (KOEO) position test for hot into the relay at the orange or pink wire depending on year. Do you have hot?

Yes, continue to next step
No, check inner panel and fuse panel fuses and replace any bad fuses and recheck

next check for hot on the Dark Green and white wire while cranking. This is a hot from the PCM to trigger the relay. Do you have hot?

Yes, continue
no, check wire back to PCM. If still not hot directly out of the PCM possible faulty PCM, or PCM power feed problem.

If you have all hot and ground at the relay next check the function of the relay itself. Do this by checking for hot at the gray Wire with your test light with the engine cranking. Do you have hot?

Yes, relay and wiring is working correctly. verify battery voltage with a Multi meter and for a break in the wire between the relay and the pump.
No. Unplug relay. With key on engine off use a fused jumper wire to apply voltage from the pink or orange wire terminal to the gray wire terminal and recheck for hot at the gray wire. if you have hot replace the relay and recheck gray wire with the relay plugged in


Here is the whole thing
http://mainstreamtopics.com/forums/i...p?showtopic=78

 

thanks! i'll give that a try. everyone else agree with him?

 

yes i do. Mine did the same thing. I went through all the trouble of replacing my fuel pump and my fuel pump wasnt even bad. I started checking my fuel pump relay wiring and i wasnt getting a hot on my pink wire. Still cant figure out y im not so i have a jumper wire on a switch right now to give me my pink but at least noew it works.

So yes i completly agree with fergymoto. It is alot easier to do that and find your problem there versus going through all the trouble to replace the fuel pump(all day job) and that not be your problem.

 

check ICM. it also sounds like fuel pump. just get a fuel pressure gauge on there to find out if you have good pressure. if not, then i'd put money on the ICM... although all things point to the pump since it won't even prime.

 

Fuel Pump takes about 45 min if you cut a Panel..

 

Couple weeks ago went out to start my car and it wouldn't start just kept turning over and wouldn't fire. I didn't have time to see what was the problem so I went out the next day and the car started right up and has been running fine ever since. Sounds like this is the problem I had. Good info guys! I will have to try some of these things out if it happens again.