Fuel level selector switch.
<hr style="color: rgb(209, 209, 225); background-color: rgb(209, 209, 225);" size="1"> <!-- / icon and title --> <!-- message --> I'll try to explain best I can, 67 F250 fuel gauge doesn't work either tank, the switch & plug which connect to it have 6 wires & terminals, I have continuity between top center terminal & top right terminal on switch when switched to left tank side, top right terminal is lead from in cab tank, switch to right tank I have continuity between top center terminal & top left terminal , top left terminal is lead to fuel gauge, when I jump left & right upper terminal fuel gauge reads full, I just filled both tanks, try jumping all other wires from plug I get no other readings ,seems to me the center terminal should be the one to the gauge since it is the common denominator but far as I can tell there hasn't been any cutting and splicing except by me when I installed a Autometer Phantom gauge, The stock fuel gauge has never worked since I owned the truck , the diagram from the fordification site isn't overly clear.I disassembled switch & cleaned the terminals & didn't see anything amiss inside.

 

I found a better diagram & I am correct that the upper center terminal is supposed to go to the gauge, the bottom 3 terminals are for a electric pump which I don't have , Now I just have to find where someone crossed the wires

 

Your aftermarket gauge is compatible with the original sending unit correct?

 

yes it is I have a auto Gage Phantom gage set up for early fords The new cluster is here, I have wrung out the wire & found where they were crossed ,the incab tank works normal now the frame tank needs sending unit replaced I have one here & tested it already just have to wait till the tank is empty Ford Truck Enthusiasts Forums - allwthrrider's Album: New Instrument Cluster