It probably has something to do with a bad ground or the thermistor may be corroded. The float can get stuck, but you would find it stuck at one point usually.
I don't have specs for your car. However, the setup is pretty common. Under the rear seat is a plate that accesses the fuel gauge arm and leags to the gas gauge and sometimes the fuel pump wires are run through here as well. Remove the back seat and the cover. Inspect the wiring for corrosion and make sure all fittings are tight metal to metal fitting and check grounds as well. Check the gas gauge by seeing if the resistance changes when moved from bottom to top out of the vehicle. If you can get it to move freely and clean the connectors, they usually work fine.

Answered by DrCranknWrench (expert)
3,292 answers provided

replace the sending unit.

Answered by cadieman (expert)
2,860 answers provided