Fuel pump wiring

GANDERSON

MEMBER
1998 GMC C1500
V8
4WD
AUTOMATIC
300,000 MILES

My truck quit suddenly after replacing the fuel pump a couple of months ago. I checked the voltage at the plug on the fuel pump on the wires going directly to the motor, I only had 5 volts at this point after some wire tracing and head scratching I checked the voltage again 12 volts. Truck started I replaced the fuel pump relay hoping that it was the problem. Drove it about three days it quit again now again 5 volts at fuel pump plug. Could someone please tell me what to check next and where does the fuel pump ground? It just goes in a clump of wires and disappears.

4 Replies

RASMATAZ

MECHANIC
75,992 POSTS

The ground point G415 is located inside left frame near rear cross member. If okay might want to check the computer control of the fuel pump relay

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Friday, January 29th, 2010 AT 6:00 PM

MEMBER1234

MEMBER
2 POSTS

You will only have battery voltage a short time after key is turned on unless you are cranking the engine. The relay will kick off after about two seconds if you just turn the key on. So you will need to have your meter connected and have someone turn key on and or crank engine while checking for battery voltage. If you do have battery voltage you can try beating on bottom of tank while someone is cranking the engine over and it may very well start. If it does the fuel pump is culprit and jarring it will sometimes make it start running.

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Sunday, July 8th, 2018 AT 4:45 PM

KENNYM51

MEMBER
1 POST
1989 GMC C1500
4.3L
V6
2WD
AUTOMATIC
126,000 MILES

What colors are the wires going to the fuel pump and which one is the hot one?

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Friday, February 12th, 2021 AT 10:10 AM (Merged)

KEN L

MASTER CERTIFIED MECHANIC
42,904 POSTS

I have found this wiring diagrams for you of the fuel pump. The wire that supplies power is tan and white. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

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