GMC Fuel Pump

Tiny
HUGH IN LOUISVILLE
  • MEMBER
  • 1999 GMC SONOMA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
I have a '99 GMC Sonoma. It quit running, and we replaced the fule pump. Could not hear the old pump running, The new one isn't running either, and the relay is ok.

What to check next?

tia
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Monday, February 21st, 2011 AT 7:55 PM

7 Replies

Tiny
JDL
  • EXPERT
Did you check for voltage and ground at the fuel pump connector? Engine cranking, use a voltage tester, gray wire is voltage black is ground. In the diagram, check the fuse circuit for voltage.
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Monday, February 21st, 2011 AT 8:03 PM
Tiny
HUGH IN LOUISVILLE
  • MEMBER
Thanks JDL, I'll check that and see. Raining here, so it may be a few hours before I know.

Appreciate the quick reply !

Hugh
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Monday, February 21st, 2011 AT 8:09 PM
Tiny
JDL
  • EXPERT
I hear you, hard to work on them, outside in nasty weather.
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Monday, February 21st, 2011 AT 8:24 PM
Tiny
HUGH IN LOUISVILLE
  • MEMBER
JDL, It was indeed the ground. We worked on it outside on the curb and I had disconnected the tail lights in order to lift the bed and scoot it back enough to get to the pump. There was a ground lug/eyelet connected to the wiring on the driver side tail lights I had un-bolted from the frame.

I took a harder look at the pump wiring and saw that there was some wiring running inside the frame going to the rear of the vehicle. That was the problem, we hadn't re-grounded that eyelet to the frame. We had tested for current initially, but not the ground.

All is well now, and it's running fine.

Thanks again friend !

Hugh
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Wednesday, February 23rd, 2011 AT 12:34 AM
Tiny
JDL
  • EXPERT
Glad you got it going your way.
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Wednesday, February 23rd, 2011 AT 4:47 PM
Tiny
MANN 1271
  • MEMBER
JDL How do I test for ground at the Fuel pump?
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Friday, January 19th, 2018 AT 11:59 AM
Tiny
KEN
  • ADMIN
Hello,

You will use a test light while the key is just turned on the pump circuit should run for 5 seconds. Use a test light connected to ground and probe the ground wire coming from the pump if it lights up the ground is bad.

Here is a guide

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

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Sunday, January 21st, 2018 AT 2:17 PM

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