I have a1968 442...gas gauge reads full (with key on) all the time.
Factory service manual says to hook up Tester BT-6508 to test gauge!
Where could I rent/buy or get an electrical diagram to build this tester.
Thank you !
edsel

 

generally when they read full the sender has failed or there is a break in the electrical circuit, i.e. the wire going to the sender broke or the ground wire from the sender is not grounding.

 

Thanks for the reply. Will check thoes things out! edsel (because that was about
the only user name not in use yet)

 

in the trunk where the wires go through to the outside there should be a plug for the sender. if you unhook it there and ground it the gauge should come all the way down, if it does the issue is probably the sender or the ground wire.

 

I grounded the wire in the trunk...the gauge dropped to empty. when I released the ground it went back to full! Will check the wire to the sending unit & the sending unit tomorrow. Thank You for your help ...EDSEL

 

Welcome to CO, I hope you can get the problem corrected, good luck.