1999 GMC Yukon fuel delivery

Tiny
DV
  • MEMBER
  • 1999 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 128,000 MILES
I have a 1999 GMC Yukon that wouldn't start one morning. After listening, I realized the fuel pump wasn't humming and or swirling. I repalced the fuel pump relay and the fuel pump started working and vehicle started.
Two days later same problem arouse, put another new relay in, and nothing. Everything seems to work when you turn the key on, even some noise at the throttle body, but no humming and or swirling at the fuel pump.
Am I right in presuming that the fuel pump is bad even though when I put the first relay in, the fuel pump didn't seem to sound any different than before the problem.
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Tuesday, September 22nd, 2009 AT 11:37 AM

3 Replies

Tiny
JDL
  • EXPERT
Did you try the prime connector for the pump, left rear of engine compartment. Red wire with electrical connector, nothing plug into it. It's just a test connector for the pump. Use a jumper wire from Battery voltage+ to the connector, the pump should run. You don't have to use the key. Use an inline fuse on the jumper. If the pump doesn't run, you'll have to check for B+ and ground at the pump connector, If that checks ok and no pump action, I suspect the pump.
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Tuesday, September 22nd, 2009 AT 4:20 PM
Tiny
DV
  • MEMBER
I tried what you suggested and found nothing like that. It is a gasoline engine and not diesel. Would that make a difference in checking if the fuel pump is bad?
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Wednesday, September 23rd, 2009 AT 9:32 AM
Tiny
JDL
  • EXPERT
You could also use a jumper wire on the terminals, for the load side of relay, to run the pump. Just make sure you have good voltage and ground at the pump before you suspect the pump.
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Wednesday, September 23rd, 2009 AT 11:10 AM

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