Hello, I read the Sticky on Fuel gauge and sender operation and diagnosis , but had a question or didn't understand since it was talking about the gauge going to empty when grounded. My fuel gauge reads empty, when I ground the Tan wire to trunk it goes to Full, then back to empty when reconnected to the gauge. Is it safe to say my gauge is fine and this is either a grounding or sender issue? Why does mine go to Full when grounded instead of Empty like Jason said? Thanks.
So your fuel gauge reads empty now no matter what? Even with fuel in the tank? Trying to wrap my head around what's going on. Sounds like a weird ground issue. Try going further upstream. Maybe disconnect the intermediate harness connector under the dash and ground the tan wire right at the dash harness and see what happens.
Yes, I looked at the Tan wire and it seemed it wasn't in All the way. I fixed it then it seemed the gauge moved a little more positive, I knew I was close to empty so thought it might have been the issue since I remembered your thread. Then I grounded it and it goes Full. So I went to the gas station and filled it. It took 19 gallons so I had about 5 in there. Still reads empty. I'm thinking its a ground issue. Either at the sending unit or in line. that's my nest step probably this weekend.
So you're saying go to harness and ground Tan wire, I should get Full or Empty? Then I'll know problem is from harness back? I have my other Riv and its sending unit works still ( I think) I think I'll just swap fuel sending units then do a bench Cal like you did in your sticky. Then I can find out the problem on the old one, fix it, and have a spare. I'll keep you guys posted, Thanks.
I read this once and that's why I thought it was the ground. Do all GM's act similar or do Buick and chevy differ? http://www.chevyclassicsclub.com/the-gm-fuel-gauge-mystery-1965-newer/
I think the problem is at the gauge, maybe the gauge ground? I would check the voltage directly at the gauge pins (after making sure connections are good). Next would be another gauge, about any of the era would work for test. good luck, Bruce Roe