EnfieldJoe

Searched the forum and did not find an existing thread to help with this issue....

Fuel gauge stuck at FULL. Started with a visual inspection of the wiring at gauge and the sending unit. Noticed that only tan and black wire are connected at sending unit. (fuel tank was replaced in 2005 by a prior owner. No history on sending unit.) Don't know if the gauge ever worked in this configuration? I've owned the car two months now and sorting out all the poor workmanship, mechanical, and electrical issues.

Upon closer inspection of sending unit, I noticed their are only two terminals, one pin type (tan wire) and one blade type (black wire). Their are no markings on the sending unit that are visible. So, the black wire with pink stripe is not connected.

Factory configuration shows that tan wire should be connected to "S" terminal and black/pink wire should be connected to "I" terminal on sending unit. Black wire should be connected to blade terminal (ground). This sending unit cannot be a GM 6428065, or even an aftermarket sending unit.

I'm thinking that the fix is to buy the correct sending unit, but I noticed in looking at a 66 that is on ebay, they also have this "one wire configuration" and the black/pink wire is not connected. I wonder if that fuel gauge works???

Anyone have any ideas?

65hihp

Pretty simple. All three wires need a contact with the sender for your gauge to operate. I suggest you buy a cheap replacement from CC or another vendor and put it in, and check for gauge function. It will probably work. Then try to track down an old original sender unit that you can replace your cheap replacement with, for long term use. Here is the page from CC.
https://www.corvettecentral.com/c2-6...%3fcount%3d180

EnfieldJoe

Thanks. That is what I was thinking, buy a Spectra FG101A first, then source the OEM part.

65hihp

I'm not suggesting a SpectraFG101A. I have never heard of that. But looking at it I see its resistance rating is 115 OHM. The original meter unit is 90 OHM. So I expect the Spectra will be less accurate than an original unit. But, it should still operate your gauge. I would buy one from CC or LICS or Paragon. Good luck.

Vitaminmopar

Please bear in mind I have the one photo you supplied and you have eyes on so my following suggestion might come to nothing. Looking at your photo the number of visible wiring terminal connections may be fooling you with the spare tire carrier in place. In your photo the ground wire does not appear to be in the correct place, which would be directly above the fuel line nipple, not off to the side. The ground wire in your photo looks to be somehow connected to the “S” terminal, if so your gauge will read full. It might be worth a second look to see if the ground tang is located above the fuel line nipple and the ground wire is connected to the “S”: terminal. I don’t know how well you will be able to feel or see with the spare tire carrier in place so you may have to drop the carrier. You will have to drop the carrier anyway to change out the sender if it comes to that. I have attached Dave Zuberer's photo from “Inside the mid-year fuel gauge and sending unit”, also attached. Cheers

EnfieldJoe

Thanks very much for the tutorial Vitaminmopar. Excellent description and pictures!

It was my intent to drop the spare tire carrier so that I could better evaluate what sender was installed prior to buying another one. I find it hard to believe that the previous owner installed a new tank back in 2005 and then never bothered to get the fuel gauge working???

I did try to swap out the tan and black/pink wires on the single pin terminal at the sending unit. Different IDs on the socket end of the wiring harness. Only the tan wire seems to fit correctly on the sending unit "pin" terminal.