1956 thunderbird gas gage

[sid's]

When the ignition is off, the gauge shows empty. When I turn the ignition on it goes straight to full. I have put 3 new floats in, checked the wire to the gauge. I have not checked the gauge because I don't know how to. They say you must send in the old one, and they will rebuild it. How can I be sure it's in the gauge? What else can it be?? Thanks..... Sid's

 

[parklane]

Seems to me that it can be checked by turning ign on, and disconnect the wire at the sending unit. Should go to empty. Then ground it, and should go to full. It has been a long time though.

 

[Ford blue blood]

That is correct.