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Fuel gauge

i own a 67 old cutlass supreme and the fuel gauge, as you turn off the car goes down to 3/4 of a tank, when you start it up it goes to full. But the car is really empty! That is the only reading I get, no matter how much gas I have. I replaced the sending unit and I cleaned the ground wire, it still does the same…anybody have any ideas???

anybody have any answers

The gauge itself is likely bad. Otherwise it should go to zero when the engine is shut off.

I agree. The unenergized movement should go to zero no matter where the sender in the tank is. The fact that it does not makes it clear that the gage is bad.

I’m not sure about a '67. I seem to recall that my Dad’s cars (such as a 1970 Plymouth station wagon) showed the actual reading when turned off, and did not go to zero. Of course, I was 8 at the time…

What happens if you disconnect the battery?

If you changed the sending unit, and assuming the new one is good, then it probably is the gauge. But you would really need a voltmeter to be sure.