[lessonsinspeed]

My fuel gauge is on the fritz. It will work fine, then the next time I glance down its pinned out over full. It goes in and out with no real consistancy. Any ideas as to the cause? Could the bobber get stuck at its highest point if I managed to hit a hard bump?

 

[bobski]

Maybe, but how would the float get launched up there? It sounds more like an electrical issue to me. If the yel/wht wire between the gauge and sending unit were shorted to ground, or if the sending unit coil was somehow shorted out, you would get the results you're describing. I'm not sure exactly how the gauge itself works, but maybe a bad ground or power source there could cause the problem?
I would try disconnecting the sender for a while. If the problem comes back, you know it's not the sender causing it. There's an access plate under the cargo bin - The sender is directly under the plate. The fuel pump wiring also runs through that plate, so you'll have to unscrew it and unplug the electrical connector from the sender itself. You won't have a functioning gauge with the sender disconnected, so keep the tank topped up.

 

[dohcrxl]

Also, try tapping the instrument cluster and see if that jogs the needle loose. If it does then obviously it's either in the connection there at the cluster or there's binding in the mechanism involving the needle. I've seen this be the problem before but just not on a rex.