The gas gauge is on the same fuse as the speedometer and the temperature gauge. So if those work, it's not the fuse.

You should be able to disconnect the wires back at the gas tank (access by taking the bottom cushion of the back seat out) and check the sender with an ohmmeter. It's pretty much standard that full is 0 ohms, empty is 40 ohms, so half full would be about 20. If you ground the wire that leads to the gauge and turn the key on, that simulates a full tank so the gauge should go to full.

 

My gauge reads full all the time and have disconned the sending unit and still reads full. checked the wires for short and all seems good.