Ok been looking over tons of old posts about this and they have helped a ton with troubleshooting. But I’m at a loss right now.

I have a 91 GMC Sierra with a 5.7 TPI out of a 91 Formula. It hasn’t run in couple of years after replacing the fuel pump. It wouldn’t start, trying to get it running so I can sell it. When I replaced the fuel pump the connector and wires were burnt. Replaced the section of wires and installed the pump and all it does now is turn over it won’t fire. Fuel pump will not prime with key in the on position.

what I have done so far.

checked relay even replaced it. Fuel pump will run jumping it from the relay plug. Also tested wire to the ecm it was good. Ground is good at the relay. Checked and replaced (just in case) in-line fuse. Fuel pump also ran when jumped from the oil pressure switch wire. Replaced oil pressure switch just to be sure. It has a vats delete chip so it’s not that. It’s got spark also.

i am at a loss to be honest. Seems to pass all the tests I can find. So hoping one of you fine gentlemen could maybe point me in a direction I haven't gone yet.

 

Is there a green/white wire at the fp relay ?

 

yes there is. I tested it. With the key on it has 12volts for couple of seconds.

 

But no 12v on cavity E ?

 

I didn’t check for voltage on E. which is the grey wire?
i did jump the grey wire with the orange wire and the pump would run. A to E

 

E should be grey or tan/white. It runs directly to the pump.
check F for being grounded if the pump runs a to e.

 

I checked the ground on F black and white wire. checked the resistance and it was less than 5 ohms. feel like it’s good.