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A few days ago, my dad's Suburban was running while sitting on a steep driveway with a low level of fuel in the tank, and the fuel pump suddenly cut out. Knowing that fuel pumps can wear out from heat when fuel level is low, we figured that the fuel pump motor had failed.

We dropped the fuel tank to replace the pump, and the new pump had a different wiring harness that required splicing the new connector into the car's electrical lines. We believe that we spliced these lines correctly.

Unfortunately, the fuel pump is not activating when turning the engine over. Normally, the pump can be heard when turning the key to 'On' and we've verified that there is no fuel pressure on the fuel rail. (the old fuel pump was also silent when it stopped running)

This morning we also replaced the fuel pump relay to no avail.

The only other piece of information that may be useful is this: When the pump stopped working initially, (before replacing the fuel pump) the engine would only crank for about a second then stop. After changing out the fuel pump, the engine now turns over without a problem.

Not sure where to go from here. Thanks in advance for your time!

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    Can you confirm if the replacement fuel pump is OE spec? If the fuel pump is priming but the fuel lines are not getting pressurized then I would revisit the wiring to make sure the motor input polarity hasn't been flipped. Some pictures of the wiring would be useful as well.
    – Zaid
    Commented Nov 27, 2015 at 3:17
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    If I have correctly found a picture of the pump, then it looks like it has 2 wires for the pump and 2 wires for the fuel gauge. Does the fuel gauge work still? If not, then you have clearly wired it incorrectly. Also check there is power getting to the new connector when you turn the ignition on.
    – HandyHowie
    Commented Nov 27, 2015 at 7:36
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    Agreeing with @Zaid here ... I would bet your wiring is not attached correctly. Also, have you tried to power up the old fuel pump to ensure that was indeed the issue? This would be to ensure your original diagnosis was the correct one.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Nov 27, 2015 at 11:27

3 Answers 3

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I believe you might have connected something wrong. Make sure that everything was spliced in properly.

Sometimes new pumps don't work very well (or at all). If the wiring is good do a test with the pressure side pumping into a gas can. That way you know if the new pump is a dud.

This is the wiring diagram for the pump circuit.

Schematic refers to platform OP asked about.

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  • Is that diagram specific to the Suburban or something generic?
    – Zaid
    Commented Dec 23, 2015 at 19:31
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    Specific to the GM platform for the Suburban chassis. Its the same for about a decade. I did look it up for this specific vehicle.
    – race fever
    Commented Dec 23, 2015 at 19:37
  • Great to have a schematic that's specific to the problem! It's a good idea to clarify it in the answer as well for future reference.
    – Zaid
    Commented Dec 23, 2015 at 20:01
  • Thats a good point. I did not make it clear that it was for the OPs vehicle. I shall do the editing meow.
    – race fever
    Commented Dec 23, 2015 at 20:06
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If I have correctly found a picture of the pump, then it looks like it has 2 wires for the pump and 2 wires for the fuel gauge.

If the fuel gauge is not working, then you have clearly wired it incorrectly.

Also check there is power getting to the new connector when you turn the ignition on.

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Thanks for all the time and input guys!

Sorry, I only just realized I hadn't posted the solution.

The pump he purchased (which did not directly interface with the electrical harness on the truck) came with a harness to splice into the trucks electrical lines (which it turns out we had done correctly), and another intermediary harness to be used between the aforementioned harness, and the pump.

The pump came packaged with a piece of paper stating in BOLD RED CAPS that it was imperative to use this intermediary harness. So initially, we did.

However, we noticed that the connectors on the spliced harness and the pump were identical, and tried connecting them directly. It worked! Not sure why the manufacturer thought this intermediary harness was necessary, but the pump and sender are working as new after a month of daily driving.

Thanks again for all the input!

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