The gauge wont do anything. Pull the fuel sender out and pull the plastic casing off the sender and you will see the actual sender. Check that it is operating properly, if it is you may just have a dead sender. While you have the unit out, you should cut the reserve line on a 45 degree angle. The reserve lines sometimes grow and hit the bottom of the tank meaning it wont pick up fuel, by cutting an angle you will eliminate this potential problem. Also while you're doing that, remove the stupid flap from the bottom of the sender unit. Idle adjustment is on carb #1.