A little help with my son’s 2003 Tahoe

[Fless]

I may have missed it or simply don't understand.

Is this a "fuel pump doesn't run" or fuel pump runs but "no crank?" Or "fuel pump doesn't run" AND the engine won't crank over?

 

[Ash4l]

Ok thanks! We probably won’t tinker with it until next weekend because it’s at my fathers house and with my work hours I won’t have time til then.

 

[Ash4l]

It’s more of I don’t know what’s causing the issue. Lol

First we thought fuel pump. No power to the pump. Changed pump and still doing it.

So we straight wired the new pump and worked great but won’t start up. It will try turning over sometimes and sometimes it won’t.

Grabbed another ecm from junk yard and tried that as well and also tried changing the ignition switch.

I feel it’s an electrical or grounding issue but I have no idea where to look.

 

[Fless]

If you bypass the starter relay, will it crank over solidly?

Have you tried the voltage drop test that I posted in an earlier post?

"Plan the work, and work the plan." -- Eric O. SMA

 

[houstontaylor]

On my 2003 Tahoe I have had fuses that did not work due to oxidation of the aluminum prongs on them. It's cheap enough to replace the fuses in the affected circuit as a precaution. Aluminum oxide is non conductive.

 

[Jeff O]

I believe the fuel pump initially charges pressure as soon as the key is inserted, the idea is that this means start is coming next. It seems the troubleshooting has already eliminated that function. I would check the main computer connectors for corrosion, especially on the lowest terminals. This fixed my problem of lack of pressure and shutdowns with no start cranking afterward.. You will note the poor placement of the main computer and its relative lack of total protection mounted on the left frame next to engine.