Fuel Gage reading off

[JeremiahBone]

I filled my tank 3 days ago and it read full even after two trips. After the third trip it kept bouncing between half and 3/4 tank. When I went to fill up again. It took 22 gallons. I'm not understanding the misread

 

[Bt Doctur]

if its a 75-80 gal tank that would be correct

 

[JeremiahBone]

if its a 75-80 gal tank that would be correct

It's a 30 gallon tank

 

[achris]

Sender needs calibrating.

 

[dingbat]

Senders go bad. Gauges go bad and wire connections can corrode.

Clean all connections from sender to gauge. If that does correct the problem, either the sender is hanging up (not likely) or the sender needs replaced.

For a quick test of the gauge, wire a potentiometer in line with the wire connected to the center of the sending unit. Adjusting pot should move gauge needle from empty to full

 

[CaptainMak]

Is it easy to get to the top of your fuel tank? If yes, you'll see 2 wires (maybe black and pink) heading that way to the top of the float/sensor.
Around 5 or 6 screws holds the float assembly down. Unscrew and pull it up and out of the tank. When you have done that, I can give you instructions how to test resistance with a basic electrical tester. You probably have a "dead spot" on the sender unit.

When mine went south, I actually ran out of fuel but the gauge showed 5/8 full.