gas/fuel gauge doesn't work

[sharkfot]

1984 Elandan-chevy chassis--for the longest time the aux gas tank gauge on the dash would read full until the tank was about a third full-then the needle would "flick" back and forth until about a quarter tank when it would register OK and drop on down with the tank level--I was ok with this because it let me know when I needed to fill the tank/it was accurate enough!  Now it is not working at all--it stays on full even through the tank is empty--I need advice on how to diagnose this--I do not want to drop the tank unless I have to--I assume the in tank sensor is the old style float/rheostat--can anyone confirm this?  Any advice is greatly appreciated--please ask questions if you need more info to help me!


Regards,


Ben III

[cncsparky]

A full or past full on the gauge indicates an open sensor circuit.  This could be caused by a broken sensor wire, bad tank ground, or the sensor stuck/went bad.  Difficult to diagnose without pulling the tank, unless you have an access panel above the tank somewhere. 

[Oz]

Start with checking the grounds.  It seems at least 75% of electrically related problems end-up being a result of that.

[Stripe]

Start with checking the grounds.

Wait, coffee can do that?!?   

[Oz]

If you spill it in your dash... oh yeah, it can do that!
D:oH!