Gas gauge always reads full


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By Dave V - 15 Years Ago
Hey guys. Can somebody tell me why my gas gauge jumps right up to the full mark when I turn on the key. It doesn't matter how much gas is in the tank. I remember an article on this at one time in Auto Restorer but I can't find that article. Thanks  Dave.
By Hoosier Hurricane - 15 Years Ago
Dave:

You didn't specify what your car is, but if it is a Ford there is an open circuit between the gauge and ground.  Could be the wire to the sender, bad sender, or lack of ground at the tank.  I always put a jumper wire from the sender to a good ground so that it doesn't matter if the tank is grounded.

By lowrider - 15 Years Ago
If its an older mid 50s to 70s Ford I think it has a short to ground going to the sender. Unplug the sender and see if it goes to empty. If it does,the sender is shorted to ground. If it doesn't the wire to the sender is shorted to ground or possibly the dash unit is bad. Unplug the wire to the sending unit and check it with a 12v test light with the key on. It should blink slowly. If it does the wiring is good. If it doesn't blink the wire is shorted to ground.
By Hoosier Hurricane - 15 Years Ago
Dave:

Dan is right, I was thinking backwards.  Disregard my post above.

By charliemccraney - 15 Years Ago
It's one of the rare, ultra efficient models they built.BigGrin