Broken Fuel Gage

[orlowted]

Hello all. I have a question on how the fuel gage works in a 65 Mustang. I just got mine on the road and the fuel gage has never worked. I recently replaced the instrument cluster to check the gage itself and that is not the problem. I also replaced the float and sending unit in the tank with a brand new one, and still no luck. From what I can tell - there is one wire running from the sending unit to the gage. There is another connecter on the back of the guage also with a wire also attached. Thinking that the wire from the sending unit was broken or split - I ran a new wire from the sending unit to the gage and it still did not fix the problem. I have to think that the other wire to the fuel gage is suposed to power this thing and it is broken, so I did an experiment. I added a small charge to the one wire going to the sending unit and the guage fired right up. The problem I have is that I just added a charge to the sending unit that sits in 10 gallons of gas and the thought of doing this scared me so I immediatly disconnected it. Does anyone know the proper way this gage is supposed to work and be wired? Thanks for any advise.