Hy Achipmunk, if you have and can use a 6 volt battery, you won't have to add the runtz into the circuit for testing purposes. If you have an ohmeter you can check the sending unit first before testing the whole system. Connect one lead of the ohmeter to the output stud of the sending unit, connect the other lead to a good clean part of the housing, with these connections in place, slowly lift the float arm up and watch the reading on the meter, it should go from 90 ohms to zero, or the other way around I can't remember which way it reads. If it passes that test then you can wire it to the gauge, output of sender to gauge terminal of gauge, gauge may be marked on the back "ign", or "+" that is the power terminal, the other terminal may be marked "ga" or "sen", that is the terminal that you want to hook the wire from the sending unit to. You must also connect a ground wire from a clean spot on the sending unit housing to part of the gauge frame, not to a terminal but to the metal frame around the operating coils, and of course back to the battery ground. So power to the power teminal of the gauge, sending unit output stud to the other terminal of the gauge, and a ground wire connecting the battery, the sending unit housing, and the gauge frame. Now slowly lift the sending unit arm and observe the gauge operation, I hope y'all can understand that, it does sound complcated, but I don't think I've left anything out, good luck, and remember if the smoke leaks out of the wires you've done something wrong
