Gas Gauge Gone Gaga!

Got a YouTube video I uploaded. This is my '90 XJ's fuel gauge going bonkers.

Took it to the nearest Chevron and filled up, hoping it would stop. But it only took 8 gallons and still reads empty/bonkers.

http://www.youtube.com/watch?v=4u3r1rrHaX8&feature=youtube_gdata

Ok, the gauge is a variable resistor, 0 ohms = empty, 44 ohms = 1/2, 88 ohms = full.

You can stop at radio shack and grab a few resistors to test the gauge itself.

Check the resistance value at the tank, you have filled it so it should be high--if not, the sending unit is trashed.

Another possible issue is a saturated sending unit float.