Car was up on stands for about a year, with a bit less than a full tank in it, and now the gauge seems to be stuck at full, no matter how much is in it. The only time it went below full, she coughed and ran out. Even then, it read full when decelerating, and empty when accelerating.

I can't figure this out; maybe i need a new float?

 

Try the sending unit on the pump. Mine was starting to act up (sticking in an over-full position) and after replacing the assembly, it works perfectly.