I'm having a problem getting my LT1 started. The fuel pump doesn't seem to want to prime when I key the ignition (key on, engine off). The pump itself is fine--I can operate it with the fuel pump prime connector near the fuse box. The relay is good, too--I check it and replaced it just in case. The dark green/white stripe wire going from pin 7 (red bank) of the PCM has good continuity to the relay from the PCM. I'm basically left with the PCM not outputting the signal like it's supposed to.

Any thoughts, or does it just sound like my PCM is shot? Any ideas are welcome. Thanks!

Dave

 

Anyone with thoughts?

I was told to check the oil pressure sending unit, but I don't see how this would affect whether the PCM sends the prime signal out or not...

Dave

 

check your ground wire that runs from the fuel injector wiring harness to the bolt on the coil.

Maybe the wire broke and you don't have a funtioning ground.

 

I'll recheck all the PCM ground pinouts and make sure the PCM itself has good ground signals for each of the four harness connections. The ground wires are definitely securely connected to the block.

Any other ideas?

Can someone verify what kind of voltage I should be seeing from that PCM pinout at KOEO? I would imagine I should see something significant for a few seconds as the PCM commands the relay to prime the fuel pump, right?

Like I said, I can manually trip the relay using the fuel pump prime connector and both the relay and the fuel pump operating fine (I get fuel pressure--verified that by looking at a gauge connected to the schraeder).

Dave

 

You should see 12v on A7 for 2 seconds when they key is first turned ON. I assume you don't have a security light.

 

This is a 96 Impala SS, but it might be slightly different than the F-Body (A7 is still the dark grn./wht fuel pump relay, however)

What do you mean by security light? I've got the pass-key light on the dash. Should I be checking something relating to pass-key? I hadn't thought about that...

Dave

 

The starter will engage and the engine will crank, so I doubt pass-key or VATS is part of the problem.

 

If it's like the f-body, you're not going anywhere with the PassKey light on. It kills the fuel pump and injectors. You left this important info of your original post.

 

I'm not sure if the light is on or not. Should it not come on at all when I put the key in the ignition? I know it lights up for at least a second when I first to KOEO but I think it goes right back out. I'm pretty sure that's normal and that it's always done that. I'll have to check it again.

Dave

 

The lamp should light when the key is first turned on, then go out. Let us know what it does.

 

I found the wire that goes to the PCM for fuel enable (it comes from the VATS module), a blue wire to A25. I'll be checking that out as well. So far I have:

1) Check PCM grounds
2) Check for Pass-Key (Security) Light
3) Check for actual fuel enable signal getting to PCM at A25

 

It turns out I had a blown PCM/IGN fuse. I had checked them all once but I must have had some temporary blindness. Fuse is replaced and all is well.

CHECK ALL YOUR FUSES TWICE

 

Better yet if in doubt check with a meter.. sometimes they LOOK good but aren't..