[boxrodz]

Sounds like you may have a loose connection.

The fuel gauge has three terminals. One terminal is the ground, another terminal is the source (+12 V) and the third one is the signal coming from the sending unit in the tank. If the connections behind the gauge are good as well as the gauge terminals then check the signal wiring/connections running between the gauge and the sending unit. If all checks out, you could check the gauge to see if it is functioning correctly. Supply a 12V between the source and ground terminals. The fuel gauge should register full when a 90 ohm resistor placed across the signal and ground terminals. It should read half full when a 45 ohm resistor is used (and so on). If your fuel gauge is functioning correctly then it may be your sending unit. You would have to pull the unit out of the tank to check its' operation. Use a meter between the ground and signal terminals of the sending unit to check the resistance as you move the sending unit arm. The meter should read between 0 and 90 ohms, You may also want to check the mechanical condition of the sending unit.

If you need to replace the fuel gauge, you'll need a 90 ohm unit.