fuel tank sending

Basically the procedure would be

1. check voltage going into gauge
2. check continuity of sender wire from gauge to tank
3. verify grounding of tank/sender
4. substitute the fuel sender with a resistor of known value to simulate the tank sender.

If all of the above check out then I would pull cluster and gauge

this thread is from a week ago and has the resistance values for the tank sender
http://www.forabodiesonly.com/mopar/showthread.php?t=184924