95 Chevy caprice fuel gauge
 

Fuel gauge stuck on 3/4 tank all the time! How do I fix this

Does it do it with the key in the off position?

Yes. It stays at 3/4 full all the time,no matter what.

Sounds like the gauge is bad.

Sender
 

It's probably your sender, the gauge might be fine. I read they get stuck a lot with these cars especially if the car was just sitting for a while. Have the same car and same problem, but yeah so you may have to drop the tank and replace it.

if it was the sender the reading would be different with KOEO. i would test the gauge