56D500boy - 2018-06-04 8:17 PM

I can't help you with the 6V vs 12V thing but I can tell you how my 56 Dodge fuel gauge works. The sender gets power via one wire that is "hot" when the key is in the ACC or RUN position. So that is your first thing to check. Are you getting 6V (in your case) when the ignition key is turned to ACC or RUN? IF not, your issue is between the ignition and the sender.

Have you checked your new sender to see that it is creating a variable resistance as the float level changes?

If you are getting 6V to the sender, is the fuel tank properly grounded? From the factory, the fuel tank is grounded via the hanger straps and/or whatever else. I was warned that sometimes in our zeal to "fix" things we paint fuel tanks that weren't painted before and, as a result, we can cause poor grounds. If you've reno'd your tank, the issue might be a lack of ground. The solution would be to create a ground strap for the fuel tank to the body/frame, perhaps a small self-tapper and a length of wire from the thickest edge seam on the tank (something that won't cause a leak) or something better and more creative (but still safe).

(Maybe scraping some of the paint off the painted tank and attaching a magnet with a screw clip and wire).

Something like this, only modified:



Reference 56 Dodge Wiring Diagram