SC02gmc

Was there a fix to this some one can post?

jstevenson3

I sure wish there was... My '03 Suburban has exactly the same thing going on. Every once in a while it won't start, no fuel pressure. When I manually connect the battery to the prime terminal in the fuse box for a second or two, the pump runs fine and builds up pressure. Then it starts and runs fine all day, fuel pressure is fine, pump is getting power.
Possibly related: I've been through 2 fuel pumps this year. Perhaps this issue is stressing the pump? Or it could be coincidental and just a bad replacement pump.

I'm not sure where to go next from here... It seems like the PCM isn't figuring out that it needs to prime. Maybe a bad connection between the ignition and the PCM? Maybe related to the fuel pressure sensor that supposedly is only used for emissions? I'd appreciate any suggestions. If I find anything I'll post back here.

jstevenson3

Update: I got a chance to probe around this afternoon. The fuel pump relay seems hotter than it should be, and when I press it back and forth voltage to the pump cuts out briefly. There's almost 0.3 V of drop between the fuse and the "prime" terminal. Swapping in a new relay didn't change anything, I'm thinking one of the terminals in the fuse block itself is bad. I ordered a new fuse block, will see if that fixes it when it gets in.

jstevenson3

Confirmed: The new fuse box fixed it in my case. Its been running fine for a few months now without any intermittent fuel issues.

RDF1

Holy cow what a old thread...

Ive fixed a AC relay and a Fuel pump relay on the GMT800s in a rush fix by take the control wires and the power / load wires, adding length to them and adding a 30/40 amp relay. Never had a problem after that.
The Terminals in the fuse block must have gotten warm and started releasing pressure. Bending the prongs on the relay helped but only for a couple weeks. Was in a hurry so used a regular relay and never had a issue. yet.