Will not start after replacing the fuel pump, the new pump is running but will not pump fuel?

Tiny
HOPE014
  • MEMBER
  • 2003 GMC SIERRA
  • 4.9L
  • V8
  • 4WD
  • AUTOMATIC
  • 184,000 MILES
The fuel pump went out, now after changing it the new pump won’t pump so the truck won’t start. I stuck the pump in the tank with no lines connected to it and it won’t even pump at all, but the pump is running. Bought 3 different new fuel pumps and none of them will pump fuel. I’ve checked the wiring and it’s correct. Before changing the pump, the truck would start but shuts off when you gave it gas, then it eventually started shutting off as soon as I would crank it up (I assume it was the loss of fuel pressure). I just don’t understand why the new pumps will run but not pump any fuel. I’ve messed with the truck for a week and can’t figure anything out.
Sunday, April 2nd, 2023 AT 11:25 AM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,575 POSTS
Hi,

Are you replacing the fuel pump or the fuel pump assembly? Next, is the strainer at the bottom of the pump clean and not plugged? Is the pump the correct one for the fuel tank in the vehicle? Does the pump reach the bottom of the tank? I ask because I've seen aftermarket ones that have an adjustable depth.

Sorry for so many questions. Chances are these are things you already checked, but I need to start somewhere. LOL

Let me know.

Joe
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Sunday, April 2nd, 2023 AT 8:57 PM

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