88 fuel gauge issue

Gauge stops working at 1/4 tank. Talked to a guy around here (he picked me up on side of highway, gave me a ride to the gas station and let me use his gas can) said he used to have an xj with the same problem. Bent float, bad sending unit, grounds, did i buy this guys old heep, or has someone seen this before??? The gauge works great other wise.

I just swapped in the whole tank and pump from a '95 and now mine reads backwards. Low Fuel light on when full and pegged on full when empty. If you find an answer, let me know.

bump . . . anyone seen this, can dig through search on this site FOREVER and find NOTHING.

On my 89 YJ I had a dirty connection at the gage cluster connector. The plug in strip was oxidized.
It never showed less than 1/4 tank.
The sending unit grounds the gage (in the early model XJ's),a tiny bit of current, any resistance in the circuit (any connector) is bound to give a bad reading.
There is a TSB, for just the opposite problem, the tank has more fuel than the gage shows. They recommend changing out the fuel pump and sending unit.