First place to look is the sending unit. It is just a Reostat(sp) like the ones found in the fuel tank. As the lever moves it either reduces the voltage or increases it making the gauge move. Bypass the sender with a jumper wire to a good ground and see what the gauge does. if it moves to either full up or full down then the sender is the problem. If it doesn't do anything then you need to work back to the gauge.
Before you go ripping it out of the dash do three things. First, make sure it is getting power. Secound, Make sure it is grounded properly. Third, make sure the wire that runs to te sending unit is not cut or disconected along it's length. A easy way to do that is with an Ohm meter. hook one probe of the meter to the wire on the back of the gauge. and the other prob to the wire at the sending unit. If the wire is in one piece the Ohm meter will show a reading. if no reading then the wire is cut someplace.
If all this fails to find the problem. Then replace the gauge.
hope it helps.
If you have any questions just email me
John F.
"Pesci O Morire"
