On My 66 Mustang the fuel Gauge reads empty but it is full! When I turn the key off the needle goes below empty. But When I turn the key to on the needle moves just a little past the E. I dont think that it is the instrument pannel because the needle would not move at all or it would just would move to the F. I am thinking that it could be the Fuel level sender. I checked the wiring and it seems fine. Do you reccomend putting a cleaner in the fuel tank to maybe clean the sender?
What do you think??

jsmth

 

Sounds like the sending unit has gone south to me.

For reference, the stock sending unit has ~73 ohms resistance at empty and ~10 ohms full, IIRC...

 

Don't put a cleaner in the tank. Most likely a wire has broken on the resistance coil. Your best bet is to get a new one. Run the tank down, jack up the front end and change it out.

 

you might have to change the float in the gas tank