I just put a used 68 gauge cluster in a former race car that has had the wiring removed. After consulting a wiring diagram, I have power running to one terminal (power with key on/run) and the other setup to run to the sending unit. To test the gauge, I have removed the sender wire and now have grounded test lead clipped on the sender terminal trying to get the gauge cluster to move. The gauge is pegged on F or past F and does not move when the key is turned on with the sender side grounded. I even tried grounding a screw terminal on the back of the gauge (although my gauges are all grounded and everything else works). Still nothing.

Am I missing anything? Is there suppose to be less that 12v going to the fuel gauge via a resistor or something not on the wiring diagram? Otherwise only thing I can think is some how the gauge is bunk. I have never seen a fuel gauge go bad, most times it is a ground or sending unit issue.

Thanks

I know that my 72 elco is pegged past full and I pulled the sending unit wire and have it unplugged because it was draining the battery.

I am actually pulling the gas tank in it to replace it with a different one tomorrow so I will let you know if I find out what was wrong.

Matt

there should be a ground coming off the sending unit.Thats where we find the problem is most of the time.

there should be a ground coming off the sending unit. Thats where we find the problem is most of the time.

sending unit appears to read correctly with multi-meter, ground should be good at sender good, and it is not hooked to the gauge at this time. Just trying to test the gauge. Guage sender side is grounded thus the gauge should read 0 ohms or empty unless I'm missing something.

every time i close my eyes i see a 70-72 cluster back side:mad: and i just finished my 68 last oct.
I'll run out in the garage and take a looksee at the 68,i'll be right back

all right.connecter has 2 wires-bwn/red.
You are saying that if you dissconect the connector at the gauge and the sending unit is still connected the muli meter readings change with the movement of the float,correct?
All we are tring to do is get the needle to move- Plug the connector in the gauge.with the key on back prob the bwn side with a known/tested ground.what happened?

all right.connecter has 2 wires-bwn/red.
You are saying that if you dissconect the connector at the gauge and the sending unit is still connected the muli meter readings change with the movement of the float,correct?
All we are tring to do is get the needle to move- Plug the connector in the gauge.with the key on back prob the bwn side with a known/tested ground.what happened?

Nothing happens thus my reasoning on believing the gauge is bad. I assume the red wire is 12v with the key on which is what I have wired to one side of mine. Other side (tan wire) is grounded. Still reads Full.

I'm actually having this same issue with my 72, but I have not dug into it at all yet due to not having a wiring diagram. From what I understand, from the sender in the tank, there should be 2 wires. 1 grounded to the frame, and 1 that runs to the guage, right? My guage is also stuck on (past) full. The odd thing is, before removing and reinstalling this BBC, the guage worked fine.........

I'll be watching this thread :D If I have any valuable input I'll chime in!

I'm actually having this same issue with my 72, but I have not dug into it at all yet due to not having a wiring diagram. From what I understand, from the sender in the tank, there should be 2 wires. 1 grounded to the frame, and 1 that runs to the guage, right? My guage is also stuck on (past) full. The odd thing is, before removing and reinstalling this BBC, the guage worked fine.........

I'll be watching this thread :D If I have any valuable input I'll chime in!
Wiring Diagram for 72 = http://elcaminocentral.com/articles/wiring/721.gif