I'm going to be picking up a '72 GMC 1/2-ton pickup that belonged to my dad. He kept meticulous records from the time he bought it in the early 70's. The fuel gauge quit working on him. He had it in a shop and they replaced the fuel sending unit. He seldom drove it and only put 600 miles on it in a year. After only 600 miles, the fuel gauge quit working again. He took it back and they put in a second new sending unit. It now doesn't work again. I doubt seriously that it is the sending unit, but am wondering if anyone out there has any suggestions as to what to look for. Apparently it worked for a while each time the sending unit was replaced, but not for long. There is a tank switch near the driver's door on the floor and I don't know if the wiring for the sending unit runs to this switch and then on to the gauge. Also, I doubt there is a fuse for this problem, but does anyone know? Anyone have a wiring diagram for a '72 GMC half-ton that might give me some ideas? Possibly a ground wire problem? Any help would be appreciated. I don't have the truck yet, but will be picking it up in the near future. Thanks.
