Fuel Gage Stuck on Full, and can't get license plate light to work

As to the gas gauge, if it is not merely a loose wire on the sending unit at the fuel tank, learn to write down your odometer miles when you fill up and then fill up again before you go too far. If the wire to the sending unit at the gas tank is fine and the problem is with the float inside the tank, the cost is too high to fix it to be worth the trouble. As to the light on the license plate, go to the autoparts store and get a new bulb and what's called bulb grease. Bulb grease keeps electical connections clean and stops oxidization forming. Often times dirt and grime makes these 12 volt connections to the bulb and ground go bad. A little bulb grease can work wonders. It's about $2 for a tube that will last a life time. Use it on flashlight batteries, too! Good luck and hope this helps.