I have a 1954 3100. The gas gauge was not working when I bought it. I have since replaced the tank, sending unit, gauge (12v) and all new wiring throughout the truck. All parts were bought from Classic Parts. Right after I hooked up the new wiring harness from Classic, I then went to hook the battery back up and all I got was smoke from under the dash. I quickly disconnected but the damage was done. The wire from the ignition switch to the "empty" side of the gauge was toast and in the process also burned some other wires and the tape on the harness. It can be repaired but I know I must not be hooking something up right. The configuration is as follows: There is a ground wire going from one of the screws on the sending unit on the tank to the body of the cab. There is a wire that attaches to the post on the middle of the sending unit and goes to the "full" side of the gauge. There is a wire on the "empty" side of the gauge that then goes to the ignition terminal on the ignition switch. I am somewhat mechanically inclined but do not pretend in anyway to be a mechanic. The truck has been converted to a 12v system. I don't know if there is supposed to be any sort of resistor or voltage reducer installed anywhere. I know Classic sells one however the gas gauge was bought new from Classic and says it is a 12v gas gauge on the outside of the box which would lead me to believe that it just could be hooked right up. Any direction as to why the wire from the ignition switch to the gauge fried and the correct way to hook it up would be greatly appreciated. Thank you in advance for your help.
Power should flow from switch to left terminal (E side), then from right terminal (full side) to sending unit in tank (center pole), then from an attaching screw to ground.
Thanks ol' chebby. I actually had it hooked up that way BUT I did finally realize the problem and thank heavens I did. I had actually taken the truck to a mechanic who had replaced a lot of the gauges. He did mentioned when he gave it back to me that he still had to work on it cause he could not get the gas gauge to work. As it turns out, when I was re-doing the wiring I came across a small cardboard panel that had fallen behind the gauges with 2 holes in it. As I was thinking it over today, it clicked. Sure enough when I looked under the dash, that piece should have been installed underneath the nuts on the gauge to insulate the power wire from grounding out on the gauge housing but of course it had not been. I hate it when it ends up being something so obvious. I sure wish the guy at the shop would have understood how important that small piece of cardboard was. I'm not really sure now if the gauge is toast. I will have to fill up the truck completely and see what registers. Thank you again for responding back. It was actually after I got your post that I started thinking things through again and I was thinking to myself "I do have it hooked up that way, there has got to be something small I am over looking", and then it clicked
