There has to be a solution to this problem somewhere. I'm back to my '72 GMC 1/2-ton sending unit problem. I've replaced the sending unit (twice now) and still have no reading on the fuel gauge. Does anyone out there have a good diagram showing how a sending unit for a '72 should be wired? This thing doesn't have a ground wire attached. There is one post on the unit for the sending unit wire and it runs to a terminal on the fuse block. When I pull the wire from the sending unit with the key on, the gauge goes to full. So then I ran the second part of this test with that wire disconnected and jumpered to a good ground with the key on. The gauge went back to empty. But as soon as I reconnected the sending unit wire, it now goes past the full mark and stays there, although I know have have about 1/2-tank of gas now. I've been told on this site that the sending unit doesn't need a ground wire as it grounds itself on the tank. I'm about ready to pull the gauge and replace it, but it doesn't seem this would be the problem. I just don't know what else to look for. I've traced the sending unit wire all the way from the sending unit to the fuse block terminal and it is in good shape. No splices, nicks, etc. Does this sound like a faulty gauge and why is it now over past full with the wire connected? Sure has me stumped that's for sure.
