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.

 

[Ash4l]

I picked my son up after work today since I had some day light left. Tried cleaning the connectors to the computer. Didn’t work.

I started jiggling some of the wires around to see if I could find a short and get the power back to the fuel pump and now it just clicks when you try to turn it over. I’m almost positive it’s coming from that wiring harness from the back all the way to the fuse box.

My son told me my volt meter was in his vehicle and now he can’t find it. So I wasn’t able to check anything today

 

[rockola1971]

If the "clicking" is coming from the starter then you have a low battery, dirty/loose connection at one of the battery cables (either end) or a Bad starter. *READ WARNING BELOW* You can take a wrench and lay it across both large terminals of the starter and it should crank the engine (wont start though). During this test nobody is needed to do anything with the key. A good starter, battery and cable connections will cause the starter to immediately spin engine over when you touch both large terminals with the wrench.

*WARNING* The 2 large terminals on the starter consist of one that is directly connected to the positive of your battery (NO SWITCH AT ALL BETWEEN THEM) and the other large terminal is connected internally to your starter motor winding. DO NOT LET THE WRENCH TOUCH ANYTHING BUT THOSE 2 LARGE TERMINALS. BEWARE OF TOUCH THE ENGINE BLOCK OR ANY OTHER METAL NEAR THE AREA! If you do, you will find out the hard way what happens when you essentially lay a wrench across the battery terminals. SPARKS EVERYWHERE AND THINGS GLOW CHERRY RED.

 

[rockola1971]

I picked my son up after work today since I had some day light left. Tried cleaning the connectors to the computer. Didn’t work.

I started jiggling some of the wires around to see if I could find a short and get the power back to the fuel pump and now it just clicks when you try to turn it over. I’m almost positive it’s coming from that wiring harness from the back all the way to the fuse box.

My son told me my volt meter was in his vehicle and now he can’t find it. So I wasn’t able to check anything today

The fuel pump should kick on for 3-5 seconds when ignition is switched to run.(Prime) During crank position the fuel pump is on full time. Listen for the fuel pump to turn on when someone switches the ignition to run for you. You can pull the gas cap and hear it really good that way, while NOT smoking.

 

[NardDog]

Hello, my son is having a little trouble out of his 2003 Tahoe. It died on him the other day and we suspected fuel pump because we didn’t hear the pump coming on. We replaced the pump but still no power to pump. Today we hot wired the pump to get it to run but it would still not crank. All fuses and relays seem to be fine. It will try to crank once then when you shut it off again and turn the switch there’s nothing. Any help would be appreciated.

So when the pump is “hotwired” HOW were you able to confirm that was OR wasn’t fuel getting to the top of the engine into the rails? With that in mind consider the checking fuel regulator on the fuel rail atop the engine. Could have failed shut.