I've seen the threads re fuel gauges showing empty but mine is now showing constantly full when I know it isn't. if I look at the number of miles till empty that is also incorrect. When I first start it, all is correct, but then the needle creeps up to full and stays that way. any ideas?

 

I had the same problem. Had replaced the fuel pump, but same. I assumed the the auto shop had checked the fuel gauge operation but they did not. The problem was the ground wires at the left hand side chassis (further away from the battery). When I tried to clean the contact, all the ground wires broke at the edges. Without the ground wires, the car would not start either. There was little room to work on the ground wires. I had to remove the left engine mount to get access to the wires. I extended the wires and mounted them at the chassis near the top. Now the fuel gauge works. Hope that this would help others that have similar problem (including car not starting).