1997 GMC Suburban Fuel Pump

Tiny
BLAHDB
  • MEMBER
  • 1997 GMC SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 13,000 MILES
Just had fuel pump and gas tank replaced by GMC dealer. Trucks, been sitting, fuel pump won't work. Fuel relay swith good(replaced). I think I'm not getting power to fuel pump, checked at electrcal harness at tank.
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Monday, September 14th, 2009 AT 9:03 AM

5 Replies

Tiny
JDL
  • EXPERT
Without dual tanks, there is an oil pressure switch in the fuel pump circuit. Once you crank it enough to build oil pressure and the switch closes, the pump will run, even without the relay. As long as the o/p circuit is functional.

Use a testlite and check that the fuse circuit is hot, ecmB mini fuse 20 amp, under the hood.
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Monday, September 14th, 2009 AT 9:27 AM
Tiny
BLAHDB
  • MEMBER
Thank-you, I'll try that, I know I have oil pressure, but I will test circuit. What about the circuit to the ECM/PCM from the fuel relay, wheres that at? Checked the fuse at ecmb and its hot still no luck
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Monday, September 14th, 2009 AT 10:30 AM
Tiny
JDL
  • EXPERT
There should be a fuel pump test connector, 5.7L gas engine. Underhood, driverside, close to firewall and relay pack, red wire with connector, nothing plugged into it. If you use a jumper wire and run B+ 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 won't run, check for voltage at the pump connector, gray wire, if no voltage, something wrong with wiring circuit.

The pcm sends voltage to the coil side if relay, in order to energize, green wire with white tracer. At initial prime, key on engine off, the pcm may energize the relay for couple second, then without rpm signal, engine cranking, the pcm won't energize the relay or injectors. But, with the o/p switch in the pump circuit, and the switch circuit is functional, the pump will run and make pressure, regardless of the relay.
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Monday, September 14th, 2009 AT 11:35 AM
Tiny
BLAHDB
  • MEMBER
Thank you for your expertise help, I hooked power to the red wire, had power to the fuel pump. Due to heart surgery truck has been sitting more than a year, no mileage, going to VA hospital tommorrow, will stop at dearlship, Dan Vaden, Sav, Ga. I live in SC, doubt they will honor the new fuel pump installed. Will let you know, once again thanks for your help. Could it go bad just from sitting?
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Monday, September 14th, 2009 AT 3:01 PM
Tiny
JDL
  • EXPERT
Did you check ground at the pump connector? If you have good voltage and ground at the pump and no pump action, sounds like the pump. Let us know.
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Monday, September 14th, 2009 AT 3:24 PM

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