The Stovebolt Site Forums The Parking Lot '60-'66 Trucks 1965 gas and temp gauge

Please what I say carefully. I have a 65 c10. It has a new wiring harness behind the dash. I redone the wiring harness under the hood. It has a new sender in the new gas tank. When I turn the key on or the engine is running the gas gauge only goes up to the first mark on the face and the temp gauge does the same. I unhooked the sender wire at the tank turned the key on it still only goes up to first mark instead of pegging out when the sender is unhooked. Any ideas what the problem is?? I have power at the fuse box which feeds the gauge until I plug in the wire feeding the sending unit then lose power at the fuse. I think the problem is affecting both gauges because they are acting the same. I have 5 gallons of gas in the tank

when i rebuilt my c10, i had to go through multiple gas sending units as they are made very cheap now. They just don't always work as they should. After 3 of them, i have a functional one. Somewhere on this site there's a good article on how to hook these up, as often it's a bad ground.

Do you have the correct wire harness? Are you using aftermarket gauges for the Temp? Only some had fairly reliable Temp gauges, it was just a dummy light or a needle that went from L to H. Best way to avoid the mess, is to get a mechanical temp gauge and put in mechanical sending unit into the engine head/block and as long as the Temp gauge works, (which you can test in a boiling pot of water before install, then you know it works). Then, you should be fine. you will just have to figure out where to mount the temp gauge in the cab of the truck. Under the dash is a good option. Some older/new Stewart warner green faces are nice look.

I have a new wiring harness behind the dash. I have done an ohm test on the gas gauge and it is around 40 ohms. The sending unit shows ohms also when I move the float up and down 0-29. I have checked the power wire going to the gauge as well and it is 12 volts. I have a new after market gas gauge coming. Will try it to see if it works with the sending unit in the tank.

Make sure you have the sending unit grounded as mentioned. If you don't have ground wire rig one at the sending unit to ground.
First step to troubleshoot

It is grounded to the cab like factory done it.