1999 GMC Sonoma Fuel gauge level misreading

Tiny
WILLIAM1951
  • MEMBER
  • 1999 GMC SONOMA
Changed the fuel pump + sending unit, but still the same problem, when put switch on the gauge goes to fuul, and after one minute, move back to empty. Even when you take the plug on the fueltank off and run the test again it keep doing the same thing. The engine runs good no problem at all with the engine only gauge fals reading. It is a 2.2L engine, the pump relay is ok. What could be the problem?
Thursday, June 13th, 2013 AT 10:15 AM

9 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
So have you checked the purple wire for the guage making sure it isn't broke or frayed? I would also check guage itself could be a bad guage. If you need help with wire colors let me know and we will see what we can do to fix it.
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Monday, June 17th, 2013 AT 8:05 AM
Tiny
WILLIAM1951
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  • 5 POSTS
I did not check the purple wire, I will do it tomorrow, and will get back to you, I was thinking about the black wire which suspose to be the ground.
Which color of wire is the ground for the gauge?
I attached one pictur of my race car, so you see I am a dragracer, It a Vega made by Bill Jenkings, runs 8.90 with a 481BB Chevy and powerglide
transmission.

Thank You,

William
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Monday, June 17th, 2013 AT 6:06 PM
Tiny
RACEFAN966
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The purple is power the orange with black stripe is pressure sensor feed that is all there is for the sending unit. The instrument cluster is grounded with a black wire there is no ground on sending unit.
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Tuesday, June 18th, 2013 AT 9:10 PM
Tiny
WILLIAM1951
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  • 5 POSTS
Ok thank you for the information, I will check both.
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Wednesday, June 19th, 2013 AT 11:03 AM
Tiny
RACEFAN966
  • MECHANIC
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Let me know how it goes and we will go from there if needed
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Thursday, June 20th, 2013 AT 7:35 AM
Tiny
WILLIAM1951
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  • 5 POSTS
We checked the purple wire with a ohm-meter from below the fuse box to the connector wire, but it seem the the meter give connectivity on
all the 3 purple wires on the fuse box. Checked the orange wire also got connectivety with the coonector.I gues the problem should be on
the dashpanel itself. It is for me verry confusion.
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Thursday, June 20th, 2013 AT 8:57 AM
Tiny
RACEFAN966
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I tend to agree. I would check what it would cost from your local parts store and a local wrecking yard. Should fix the problem.
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Friday, June 21st, 2013 AT 7:26 AM
Tiny
WILLIAM1951
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  • 5 POSTS
Yes thats what we onna do see if we can find one (wreckiing yard) locally, otherwise I have to order one. I will let you know.
Thanks.
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Friday, June 21st, 2013 AT 11:51 AM
Tiny
RACEFAN966
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Sounds good
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Wednesday, June 26th, 2013 AT 8:07 AM

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