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Fuel pump not working - low pressure

Tiny
DARRENBRANDT
  • MEMBER
  • 1999 GMC JIMMY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
1999 gmc jimmy 4.3l. Just replaced the fuel pump and two days later the fuel pump stopped working. Pulled out the new fuel pump and replaced with a another new one. My question is what would cause the new fuel pump to go out? I know there is a possibility that it could have been just a bad fuel pump or I was wondering if there could be another kind of electrical problem that would cause the fuel pump to go out? Any suggestions?
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Sunday, April 24th, 2011 AT 9:13 PM

26 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check and test the fuel pump fuse, fuel pump relay and the fuel pump and oil pressure sending unit-also test for voltage drop problem
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Sunday, April 24th, 2011 AT 9:18 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
They have a known problem with the contacts in the plug at the tank.
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Sunday, April 24th, 2011 AT 9:31 PM
Tiny
DARRENBRANDT
  • MEMBER
  • 5 POSTS
I did just find that the oil sending unit was unplugged. How would the oil pressure sending unit affect the fuel pump? How can I tell if the fuel pump relay is bad?
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Monday, April 25th, 2011 AT 2:05 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
The oil pressure sender is a redundant power supply to the fuel pump. The truck can run with either/or working properly but if it loses both, it will not run so there is a good chance you have a problem with the relay. When running on the oil pressure switch only, you will have a long crank before starting because you aren't getting the 2 second prime supplied by the relay.
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Monday, April 25th, 2011 AT 2:09 AM
Tiny
HISHAAMHENDRICKS
  • MEMBER
  • 1 POST
  • 1998 GMC JIMMY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 164,000 MILES
The car stood for 3 months with 1/4 tank of petrol. Initially the car started after this period, but then stop working after a week. Initially, I thought that it could be the battery as the indicator was white but after replacing the battery the problem still persisted. When the carburette cover was removed and petrol was poured into it then the car started. What could be the solution if the petrol pump works?
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,645 POSTS
First, we need to make sure the pump is producing enough pressure to run the engine. Here is a how to for checking pressure.

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Let me know what you find.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIM HOFER
  • MEMBER
  • 4 POSTS
  • 1998 GMC JIMMY
Engine Mechanical problem
1998 GMC Jimmy 4 cyl Four Wheel Drive Automatic

not getting any gas. Fuel pump is not running.I replaced fuel pump already. Why is fuel pump not running not running?
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Hi, did you check for voltage and ground at the pump connector, engine cranking? Gray wire is voltage, black wire is ground. Without voltage and ground, the pump won't do anything. Next, I check voltage circuits at the fuel pump relay, use a dmm to check for voltage. I'd also check fuses.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIM HOFER
  • MEMBER
  • 4 POSTS
Engine is cranking good. And fuses are good.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
You need to check for voltage at some of the circuits I mentioned.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIM HOFER
  • MEMBER
  • 4 POSTS
Fuses are good. Relay is good. Pump only works first time I turn the key. If I unplug it and plug it back in it only works the first time
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIMMY95
  • MEMBER
  • 5 POSTS
  • 1995 GMC JIMMY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 171,000 MILES
Ok I was driving on the higjway, so the trucks just shut off, towed back home, so no fuel pressure at all, I replaced the relay, nothing, put a new fuel pump, nothing, no pressure, fuel pump just wont kick on, I use a hot wire to power the fuel pump in the harness right there on the top of the fuel tank, but nothing, a faulty sending unit can be possible, dont let power the fuel pump? Do this truck has a shut off valve or switch, thanks.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Power the fuel pump connector gray wire from the battery positive post did it come on if not check the black ground wire to it. If okay think! Fuel pump again
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIMMY95
  • MEMBER
  • 5 POSTS
I tested the old fuel pump, I power it and it works! That means the fuel pump wasnt the problem.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Where are you checking the fuel pressure? Is this the spider Vortec fuel system come on back
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+1
Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIMMY95
  • MEMBER
  • 5 POSTS
It say vortex, but is not the spider one, this is a 95, I put my gauge at the fuel rail, pump is not kicking on at any time, check the fuse, but is ok, I put a new fuel pump relay, fuel filter was replaced a month ago, I didnt check the black ground wire, I put the hot wire in the middle of the harness at the fuel tank and sparks! I put the new fuel pump, with the new inside harness, can the sending unit be shorted?
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
GEF4132
  • MEMBER
  • 3 POSTS
  • 1994 GMC JIMMY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 126,000 MILES
I checked fuel pressure it low.I also sprayd starter fluid in manifold it ran for a few sec. Pressure regulator change, fuel pump change and fuel filter changed. Getting fuel to injector pump what cani try next?
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The gray wire powers the fuel pump-Sparks you shorted something out could be the pump or the sending unit.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
How low is the fuel pressure? It should be 55-61psi if not in this range injector/s could be leaking and dropping the pressure. Also check if the injector/s are pulsing if not could be power source to it or the computer's injector drivers.
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-1
Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIMMY95
  • MEMBER
  • 5 POSTS
Well I put the new fuel pump and hook up every thing, I turn the key on, and nothing, then I did that with the hot wire, I will check it tomorrow, if smthg happen I will let you know of course I will not forgot about the donation thanks for your time.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)

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