In my 1991 jeep Cherokee, I filled up the tank, but the gauge still had the light and read empty. About a day later the gauge shows 1/8 a tank instead of empty. How can I fix this?

 

Disconnect the connector going to the fuel pump/sending unit and check the resistance of the sending unit.

 

it could also be a bad ground at the tank

 

How do I test for that?

 

The resistance on the tank side is about 90 ohms. On the gauge side, if I connect the prongs on the wiring harness, the gauge reads full, if it is unplugged, it goes below empty. 30 ohms of resistors make it go halfway, so the gauge seems fine. When the tank is around half full to full, the gauge reads 1/8 of a tank. When it is around less than half, it reads empty.
Does this mean that the float mechanism or potentiometer is bad? I read on another forum that someone fixed it by putting multiple bottles of techron in their fuel over several tanks.

 

Is it possible to take the float mechanism out without dropping the tank to clean it?

 

my moneys on the ground wire it could be corroded or frayed. follow that harness.

 

Can it be bad inside the gas tank?

 

The problem was that gas got inside the plastic float making it not read correctly. It worked fine in water, but apparently gas has a different specific gravity. I got the gas out of the float and melted the hole I made and the seams. It works now!