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Tiny
SSROBERTSON
  • MEMBER
  • 2000 GMC SIERRA
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I bought a non running project truck (listed above). My problem is a few actually, first I'm not getting power or ground to the fuel pump. Fuel pump, and filter are new and can force pump to run by running straight from the battery. I have checked all fuses and relays. Truck will run at this point.
Second issue is: I cannot get the instrument cluster to light up mileage, security, fuel level and temperature gauge. The voltage, speedometer, tachometer (I think), check engine light all come on. I have bought a new body control module that was already programmed to my VIN and it does the exact same thing. Even swapped used gauge cluster from the junkyard and it does the exact same thing. I'm at a complete loss on this thing and just need some help. Thanks in advance for any help that can be given.
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Sunday, May 2nd, 2021 AT 7:43 PM

34 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

I attached the wiring diagram for you of the fuel pump and the engine control system.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Check at the relay for power at terminal 30 with the key in the on position. You should also have power at 85 for 2 seconds with the key on. Then when you crank it, it should be full voltage.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Roy

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Monday, May 3rd, 2021 AT 5:02 AM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
I have checked fuses and relays but I will check some of the sensors to see if maybe that could be the issue. The truck will start and run if I run the fuel pump direct from the battery. One of the most confusing parts is the issue with the cluster.
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Monday, May 3rd, 2021 AT 5:53 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
It is not a sensor at all.

You need to do the voltage checks I suggested to see what is not allowing voltage to the pump.

Roy
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Monday, May 3rd, 2021 AT 6:01 AM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
Okay. Will do. Any chance the two things (fuel pump and cluster issue) are related?
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Monday, May 3rd, 2021 AT 6:05 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
No, they are not related.

We can address the cluster in another question. We can only answer one issue at a time as per site rules.

If you start a new question, I will be happy to help with the cluster issue.

Roy
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Monday, May 3rd, 2021 AT 6:24 AM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
I was unaware of that. I will make another question for the cluster. Thank you
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Monday, May 3rd, 2021 AT 6:25 AM
Tiny
ASEMASTER6371
  • MECHANIC
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You are welcome.

Always glad to help.

Roy
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Monday, May 3rd, 2021 AT 6:26 AM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
Checked voltage at cam position sensor and have 5 volts on white wire (far right in picture). Also checked fuel pump relay terminals and getting power on 30 and 2 seconds on 85. Had helper cycle key and rechecked at pump still no prime or power while cranking. Also appears no ground either.
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Monday, May 3rd, 2021 AT 5:51 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, when you turn the key to the on position, does the relay energize and click?

If it does, check the wire from 87 to the pump. If it does not, then yes, it could be the ground for the control side of the relay. The ground is G117 in the diagram and it is located on the rear of the engine. It is usually on either the cylinder head or it could be attached to the bell housing bolt.

Roy
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Tuesday, May 4th, 2021 AT 3:16 AM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
The relay does click. I had a feeling it could be that wire was damaged (I had to do this on a friend's truck before, seems like it's common). I will try to run a new wire and see if it resolves my issue. I will keep you posted. And I did put through another question for the cluster issue. Thank you for your help Roy!
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Tuesday, May 4th, 2021 AT 3:24 AM
Tiny
ASEMASTER6371
  • MECHANIC
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You are welcome.

Keep me updated.

Roy
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Tuesday, May 4th, 2021 AT 3:32 AM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
Update: I ran a new wire from 87 to fuel pump and now have power as I should. Only thing I noticed is I had to ground the fuel pump to make it come on. Other than that it works perfectly now.
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Friday, May 7th, 2021 AT 2:38 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Good job.

How does it run?

Roy
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Friday, May 7th, 2021 AT 3:21 PM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
I haven't got that far yet, lol. Still an ongoing project.
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Friday, May 7th, 2021 AT 3:43 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, keep us updated.

Roy
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Friday, May 7th, 2021 AT 3:50 PM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
Will do Roy!
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Friday, May 7th, 2021 AT 3:55 PM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
Hey Roy, once I get this truck fired up it runs pretty rough and wants to stall at first "cold blooded". But while you are trying to get it to smooth out it has a decent amount of smoke out of the tailpipes. It's running very rich. Now keep in mind this truck hasn't been driven much over the last few years, but always garage kept. I'm sure some of it may be condensation from sitting but not sure why it runs like an old loaded up carburetor. It has new Delco iridium plugs and newer wires.
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Monday, May 10th, 2021 AT 5:52 PM
Tiny
ASEMASTER6371
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Did you drop the tank and flush out all the old fuel and change the pump? If it has been sitting for years, the fuel is no good at all.

Roy
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Monday, May 10th, 2021 AT 5:55 PM
Tiny
SSROBERTSON
  • MEMBER
  • 80 POSTS
Yes I did. I replaced the fuel with 93 and a bottle of decent fuel injector cleaner. It also has a new fuel filter, but it was changed just before I drained the fuel. I think it should be fine since the tank is plastic and the fuel didn't seem to have any junk in it. I also did replace the pump.
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Monday, May 10th, 2021 AT 6:00 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, change the filter again. You still have old fuel in the lines. It will take time to get that out.

Roy
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Monday, May 10th, 2021 AT 6:33 PM

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