Fuel delivery

Asked by GuruB1BC9 Jan 04, 2019 at 06:01 PM about the 1990 Chevrolet C/K 1500 Silverado RWD

Question type: Maintenance & Repair

I have a 1990 Chevy Silverado and I dont have enough
power to the fuel pump plug to turn the pump on. What
controls the voltage to the fuel pump. I can run a straight
hot wire from the battery to the pump and it will run and I
can crank the truck and let it run but that's the only way.
What could be the problem. Thanks in advance.

2 Answers

35,335

It could be a blown fuse to the fuel pump relay or the relay itself. Trace it back from the pump to the battery

I just went through the same thing on my 89 silverado w/5.7 eng. No run but cranks, yep I changed fuel pump after I fought with the fuel tank strap bolts. Had to go buy a half inch impact gun to get them loose. Anyway I think your checking voltage on your sender wire not pump wire. You will see a voltage drop because the potentiometer will create that resistance. Make sure when testing fuel pump circuit you must check voltage on gray wire at relay or tan wire at pump harness and solid black which is in truck side harness that then connects to solid black coming from pump not at the plug. Should be12v. and will light your test light if available

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