Fuel pump with LS engine

[Ramiro0727]

So my boy swapped his heads out and he was putting the headers back on the fire it up again and when he was connecting the battery again he accidentally arched the battery and now the fuel pump won’t prime or even turn on unless we put power directly to the fuel pump itself. We checked the power to all the fuses and they have power we’re just not getting power to the back part of the truck now. What else can I do to try to troubleshoot the problem.

Thanks ,
Ramiro

[gmc684x4]

Look at all fuses sounds like a popped fuse
I am going to say what ever fuse that controls fuel pump relay is blown

[Ramiro0727]

Originally Posted by gmc684x4

Look at all fuses sounds like a popped fuse
I am going to say what ever fuse that controls fuel pump relay is blown

gmcc684x4 I checked every fuse with a test light. No fuses are blown. The ECM wouldn't be blown would it?

[gmc684x4]

possibly ecm

Did you check both fuse panels the one under the dash as well as the one under the hood ? are there added fuse holders by the battery to check as well

The main fusible link will be easy to test check if you have 12 volts to the big alternator wire

[rayce88]

Check the Fuel pump relay ?

[Ramiro0727]

Originally Posted by gmc684x4

possibly ecm

Did you check both fuse panels the one under the dash as well as the one under the hood ? are there added fuse holders by the battery to check as well

The main fusible link will be easy to test check if you have 12 volts to the big alternator wire

gmc684x4 i will check the alternator wire for 12 volts.

[Ramiro0727]

Originally Posted by rayce88

Check the Fuel pump relay ?

rayce88, i checked the fuel pump relay and it did have 12 volts to it. all fuses were good.

[rayce88]

Originally Posted by Ramiro0727

rayce88, i checked the fuel pump relay and it did have 12 volts to it. all fuses were good.

Well then I would would check for 12volt out of ecm to fuel pump but before relays with key on ... If you have that then ecm should be good ... I would change relay anyways just to rule it out as relays are very sensitive to power surges ...

[Ramiro0727]

Originally Posted by rayce88

Well then I would would check for 12volt out of ecm to fuel pump but before relays with key on ... If you have that then ecm should be good ... I would change relay anyways just to rule it out as relays are very sensitive to power surges ...

raycee88 I will try to check for 12 volts out of the ECM to the fuel pump. Now to try and figure out which wire it is. Yes we did replace the relays also.

[SkidmoreGarage]

What do you mean by "arc-ed the battery"? If it just sparked when getting connected, I'd be surprised it fried an ECM (assuming a good wiring harness). If it was hooked up backwards... Or if the header install crushed some wires that shorted out... Then it would make more sense. Without knowing your exact wiring, have you confirmed that you are getting the constant power as well as the signal to the relay? If the relay appears to be getting a signal and it's a known good unit, try applying 12v directly to the relay power feed and see if it passes through to the pump with key on.

If you don't have a cheap multi-meter, I'd recommend picking one up. Checking for continuity would help you a lot.

[Ramiro0727]

Originally Posted by SkidmoreGarage

What do you mean by "arc-ed the battery"? If it just sparked when getting connected, I'd be surprised it fried an ECM (assuming a good wiring harness). If it was hooked up backwards... Or if the header install crushed some wires that shorted out... Then it would make more sense. Without knowing your exact wiring, have you confirmed that you are getting the constant power as well as the signal to the relay? If the relay appears to be getting a signal and it's a known good unit, try applying 12v directly to the relay power feed and see if it passes through to the pump with key on.

If you don't have a cheap multi-meter, I'd recommend picking one up. Checking for continuity would help you a lot.

SkidmoreGarage he was tightening up the negative battery cable using a ratchet. the ratchet hit the positive post and it arc-ed. we are using a american autowire power plus 20 wiring.

[SkidmoreGarage]

Understood, it's definitely possible to damage a lot of things with a current spike (especially in the ECM), but I'd be surprised if that is the case with the key off and arcing directly to the terminals. The electrons will take the path of least resistance, which is through the wrench. I'd also make sure your battery isn't dead by trying another battery.

I would look for melted or loose wires around where the work was done, it's possible a wire was pinched or a ground was left off.

It looks like there is a wire in your harness that is labeled fuel pump. I'd make sure this is getting 12V at the fuse panel and the relay. If that checks out, test to see if the relay is switching. Then manually switch the relay with a jumper and see if the pump runs. This will eliminate pump wiring.

[Ramiro0727]

We did what everyone recommended. We finally got the the fuel pump to power up. Turned out to be a bad ground from his engine to the frame. Thanks again for everyone who responded to my post.

Ramiro