Hello Wes Thomas, Welcome to Stovebolt.com
To test if the sending unit is working there should be 5 or 6 screws on the top of the sending unit. Unhook the battery to guard against sparks. Pull up on the sending unit and look at the position to see if it is floating on the gasoline or is it installed sideways where the float is rubbing on the side of the tank. If so, then turn it to a place where it will move with out the float hitting the tank and the screws line up, adjust as described below. If not continue the test this way; Remove the sending unit. Move the sending unit as far away from the gas tank and stuff a rag into the SU hole to stop the gas fumes from making their way towards the place you are working. Get it as far away as the sending unit wire will let you. Use a jumper and hook the sending unit up to ground on the edge of the medal top, you can put a screw and nut through a hole to do this temporally to get a ground. Turn the key on. Slowly move the arm up and the gauge should start to move towards full, move the float arm down and it should move towards empty. If the aluminum tank you have is flatter and spans the frame the float moves up and down a lot less. The way to adjust a aftermarket sending unit is to bend the float arm to match as closely as possible to the gas height. When the gas is low or empty the float should be in the down position to show empty. When full the inverse happens the float should be to the top to show full. If moving the arm doesn't change the gauge on the dash you can use a voltage gauge to see if the voltage changes as you move the arm. This part is speculation from me, the 6 to 12 volt conversation may need a voltage step down to keep the gauges 6 volt. If the gauge goes all the way from full to empty with the sending unit out of the tank the problem is the arm adjustment as described above and not the voltage. Good Luck. John
