67-72 Chevy Truck fuel gauge diagnostics 101

[TBONE1964]

Originally Posted by Hoodogie

I know this is an old post but I hope someone will direct me a little bit. Not being great at electrical work I have read the previous threads and checked some things out with my gas gauge. Let me start and say that the gauged worked fine before I removed the cluster to change the printed circuit on the back in order to get my dash lights working. When I reinstalled it the gauge was reading at three o'clock. I then reached up behind the dash and found out that I haven't tighten the nuts down on the gauge terminals. I don't know if I had the key on or not but as I was tightening the nuts the gauge went from 3 o'clock to 3/4 full and hasn't moved since. I checked the resistance at the tank and got 68 which is what I think is correct for the gas I think is in the tank. When I remove the tan wire from the fuse box nothing happens to the gauge. When I grounded the terminal nothing happens with the gauge. Did I blow the resistor when I was tightening the nuts up I'm stumped

It sounds like you have lost the power to the gauge. My first question is does the temp gauge work? Make sure the temp gauge works before anything else is done.

If the temp gauge does not work, check for battery voltage at the #3 terminal of the cluster connector. You should have voltage with key on. If not, check the gauge fuse.

Also it is critical that the circuit board tangs where the connector plugs in have not moved and caused a short. Over years they do come loose. Yu can repair with a dab of super glue if needed.

If you suspect the resistor is bad, remove it from the gauge and test it with an ohm meter from one side to the other. You should have approx 85 ohms.

The gauge will set at the 3 oclock poistion when it looses ground or the tan wire is not connected, which is the signal wire from the sender.

The gauge will stay where ever it stopped after ign is shut off or the gauge looses battery voltage.

Hope this helps,
Tom