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1997 GMC Yukon fuel pump not cycling

Tiny
GREASERALL7
  • MEMBER
  • 1997 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 162,000 MILES
I have just replaced a bad fuel pump in a 1997 GMC Yukon and while the old pump did nothing at key start or during test the new pump cycles when tested but will not cycle to prime with the key in the on position nor will it run when the engine is cranked. What could it be? I already changed the relay and have found no bad fuses.
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Tuesday, March 22nd, 2011 AT 2:44 AM

6 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Wire the fuel pump direct from the battery and see if it'll start up-if so check the computer controlled of the fuel pump relay circuit-
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Tuesday, March 22nd, 2011 AT 2:51 AM
Tiny
GREASERALL7
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  • 4 POSTS
I'll give that a try in the morning thank you.
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Tuesday, March 22nd, 2011 AT 3:11 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Okay-let me know your findings
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Tuesday, March 22nd, 2011 AT 3:19 AM
Tiny
GREASERALL7
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  • 4 POSTS
Really quick would a bad oil pressure sensor cause this symptom also by not activating the pump?
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Tuesday, March 22nd, 2011 AT 3:25 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
I was fixing to give you that-when the fuel pump primes the system before the relay deactivates and fires up and then dies we can blame it to the fuel pump and oil pressure sending unit-

When the engine fires up-the FPOPS-powers the fuel pump at all times-Good Luck
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Tuesday, March 22nd, 2011 AT 3:28 AM
Tiny
GREASERALL7
  • MEMBER
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Alright im a little embarrassed because I checked all of the fuses with a multimeter and again visually. I found that the ecm b fuse was blown when I checked them again yesterday. I replaced the fuse and as soon as I turned the key everything cycled like it was supposed to. The yukon started and runs fine now but it was a diagnostic nightmare to end up finding something so simple. I did short the pump to power to test it and it ran fine, I checked the wiring and fuses all seemed to be fine but the one that was blown showed okay during a continuity test with the multimeter. But its running now and I thank you for your advise.
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Wednesday, March 23rd, 2011 AT 8:34 PM

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