The fuel gauge in my 78 3/4 has not worked since I have owned the truck. So today I decided to try to do something about it. I figured that it might be the gauge itself because nothing happens when I flip the tank switch, so I popped open the cluster and replaced it along with a few lights and the clear plastic. That was not the problem. I did some snooping around under the dash and found that the previous owner had cut the blue wire coming from the selector switch and fed it into an aftermarket autometer fuel gauge that also doesn't work. So I re-hooked that wire together and still nothing. When I installed the other gauge I set it to E and when I turned the ignition switch the it shot up to way past full. I understand that this indicates a bad sender but it does nothing different at all when I flip the tank switch, and I know that that works. I suppose that both senders could be bad.
How does the gauge know what tank to read? Is there a switch motor somewhere for that that I have not come across? I kind of thought that it would be fed through the tank switch itself, but all of the wires coming from that run outside the cab except the pink/black that just goes to the fuse block. So how do the senders reach the gauge?
Thanks
Ill
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