Bartamos - Thanks for your reply. Actually, when I disconnected the wire from the sending unit behind the seat, I thought the same as you stated here. That is, why would there be a connection that goes to the fuse panel? It should go directly to the gauge. However, further research provided that the sensor wire is plugged into the left side of the fuse panel - second spade connector up from the bottom (look at a '66 fuse panel in the internet ) and you can see that spade connector is labeled "fuel gauge". On the backside of the fuse panel - attached to the other end of that spade connector is a brown wire that goes to the fuel gauge. So essentially, the sender wire connects to the fuel gauge though the fuse panel. I don't believe there is any power there - just a connection. And to restate, this all worked after I ran a new wire to the new tank sending unit and made the connection. It was a week after I hooked everything up that the gauge started reading "full". The ground wire from the sending unit is connected to a clean, bare frame connection made on the truck frame near the gas tank. In another post related to backup light issues, another Stovebolt contributor suggested that my '66 may be wired more like a '67. When I was installing the gas tank and wiring the sending unit, the full reading occurred then as well. I finally discovered that if I moved the fuse panel slightly the gauge read the proper level. That is when I discovered that the bottom screw that secures the fuse panel was missing. I replaced the screw - and the gauge worked after I tightened the panel to the firewall. Then, as I said in my post, after moving the truck and driving it a short distance, the gauge went back to reading full. Which is why I wondered if there was some form of insulating spacer behind the fuse panel that kept it from grounding against the firewall. So.. I am still puzzled.
Last edited by Tim-o; 06/30/2018 11:58 PM.
