Question about 1999 GMC Sierra

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The fuel pump on my 1999 GMC Sierra is not working.

The fuel pump is not working and I checked the relay by replacing it with a known working relay, checked for fuel at the schraeder valve next to the throttle body and there is no pressure there. I also loosened the back side of the in-line filter and it appears to have fuel flow there. I don't know how to check for power at the pump itself without removing the tank. Until recently when the truck ran out of gas (with 3/4 of a tank) it has been getting harder to start as it was always easy to start and would fire up after about 1-2 spins, but before it quit I have had to crank it several times to get it to start.

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Never tried it, but it should work because it\'s a pain to drop the tank and eyeball it. Electric fuel pump in the tank... ok. It\'s a motor and motors draw current right? One could -possibly- yank the fuse and replace it with a ammeter (DVM on Amps). If the circuit is complete, it should pull 3-4 amps minimum when the pump is running I\'d think. If the circuit is open, it won\'t draw anything, zero or close to it. There may be a small draw from other stuff that\'s on the fused power but the difference should be obvious. Better yet, drop the meter into the relay contact circuit. The only thing that should be on that one is the fuel pump itself. Put one lead on the +12 battery and the other lead into the contact block that goes to the pump. It should turn on. If you\'re squirmish use a pigtail fuse at about 4 amps. The coil and contact arrangement is usually printed on the side of the relay. If not, the contacts are usually on beefier terminals than the coil. If all else fails, get the chassis service manual and look up the color codes.

Posted on Dec 26, 2013

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Posted on Jan 02, 2017

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SOURCE: I have a 95 GMC Sierra 1500 that while driving, it


Many big and small things can cause this, but i think it's something like a ecu failure, ignition failure, a short-circuit...

contact your local tecnician to point it out, or a specialist maybe, cause its too hard to just say what it can be caused by.

I hope this is useful, and greets,


Posted on Oct 21, 2009

Testimonial: "Good answers. At least I know of a few more things to check out. Thanks Olivier"

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SOURCE: I have a 1989 GMC sierra 4.3 Liter, fuel pressure

u can do the check the other way around/ disconnect the fuel line that supply the injectors/ put the pipe in a small plastic container to see if fuel is being supplied by the pump and avoid fuel spill in ur engine/ crank the engine for at least 5 seconds see if the fuel squirts with pressure/ if it does then ur fuel pump is ok / blockage is somewhere down the fuel line/ u can check fuel lines by blowing it with air but u gonna need the help of an air compressor.....

Posted on Apr 09, 2010

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