1977 C10 Gas Gauge

[casey3115]

First time posting. I have a 1977 C10 and the gas gauge is on the fritz. A few weeks ago the gauge pegged itself way past full and stayed there for a few days. One day I started the truck and the gauge slowly went back down to around a 1/4 of a tank which seemed about right. All was well for a few weeks until the other day it pegged way past full again. This time it only lasted until I started it again. Then tonight it did it again, went way past full and stuck.
Any ideas? Is this the sending unit or something (fingers crossed) more accessible like a fuse?

Thanks all in advance for the help

[Dead Parrot]

Gas gauge reading at 3 o'clock is almost always a bad connection somewhere between the gauge and the ground stud off the sender on the tank.

Open circuit - 3 o'clock reading.
Wire shorted to ground - empty reading.

41 year old wiring has lots of places for corrosion to do its thing. If dual tank, switch is also a prime suspect.

[hatzie]

Originally Posted by Dead Parrot

Gas gauge reading at 3 o'clock is almost always a bad connection somewhere between the gauge and the ground stud off the sender on the tank.

Open circuit - 3 o'clock reading.
Wire shorted to ground - empty reading.

41 year old wiring has lots of places for corrosion to do its thing. If dual tank, switch is also a prime suspect.

I've seen this behavior on three of these trucks.
The sender ground is damaged or missing. The tank strap is making intermittent contact with the tank making the gauge work intermittently.

Clamp a jumper cable from the tank pinch weld to a clean spot on the frame and watch the gauge work normally.