Fuel Guage malfunction - 1978 FJ40 (1 Viewer)

[keithianminton]

Turned FJ on today fuel guage was reading fine with 1/4 tank full. Turned off guage went to empty like normal. Started back up a few minutes later and the needle went to past full position. When I turn off the needle slowly goes back to empty….confirmed fuel level in tank and it was at 1/4 full. Would this be a guage that has gone bad or would this be a sender issue and need replacement? Thanks for all the help.

 

[B y r o n]

They make fuel additives that are designed to remove buildup on sending units and getting them to function back at 100%. Maybe trying one of them to resolve the issue.

 

[Skreddy]

I would check connections first. If I remember right, past full with key on is a disconnection somewhere in the path? (Or was past full a ground somewhere in the path…..)

 

[Living in the Past]

I would check connections first. If I remember right, past full with key on is a disconnection somewhere in the path? (Or was past full a ground somewhere in the path…..)

I know on my 68 when the wire came loose on temperature sending unit the temperature on the guage pegged past high.