The gauge works great until about half tank then it goes to empty...climbs to half...goes to 1/4 tank etc. Im thinking the only thing it can be is the float in the tank? Does the whole fuelpump have to be purchased? Any easy access to the fuel pump on the 91 ls400? Thanks! :)
The fuel gauge sender is separate from the fuel pump and fuel pressure regulator. The fuel gauge sender is basically a float on an arm, and as the arm moves up and down, the voltage from the fuel sender goes up and down, and the fuel gauge is basically a volt meter.
If the gauge varies, it is possible that the float got detached from the end of the arm and so it is sliding on the arm, the potentiometer in the fuel sender is going bad, or there is loose or corroded wiring somewhere.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.