VCCA Home Forums Thread Like Summary - Gas Tank Sending unit

I just did my 1935 Chevy master deluxe gas tank and sending unit. When I put the gas in all the way, full and red almost empty so I accidentally did something backwards on the sending unit. I was wondering is there any other way to fix this besides taking the tent down, does anybody also know what the two connections on top of the sending unit or four if I flip them around with my gas meter go back to normal or does one pacifically go to another one. I did grounded to the car. Any suggestions would be very appreciated. Thank you so much.

Sorry for the confusion on my part. I suggest that you need to get back to the basics and use an organized troubleshooting approach. Randomly changing wires is obviously not solving the problem.

Do you have a wiring diagram for your vehicle? That is where I would start. Get one and trace each wire that is part of the gas gauge circuit end-to-end. Do a continuity test on each wire and make sure that none of those wires are shorted/grounded. Then confirm which wire is the hot wire that powers the circuit.

There is one other key test I do whenever I am working with a fuel gauge circuit. I always test the sending unit out of the tank to make sure the movement of the float arm will move the gauge needle properly. I do this before I install the sending unit into the tank.

I connect the wire from the gauge to the terminal on the sending unit. I connect a jumper wire from the sending unit housing to a good chassis ground. Then I turn the key on and move the float up and down while I (or someone else) watch the gauge.

That test has saved me a lot of time and grief when there are issues after the sending unit was installed. If the gauge worked correctly before I installed the sender then I knew the problem was related to the installation or something in the tank. In one case we determined that sending in unit was incorrectly grounding itself upstream from the rheostat. In another case we determined that the cork float was defective. It was so saturated with gasoline that it would not float above 1/2 of the tank depth even when the tank was full. Also it hardly registered until you have the tank at least half full.