Hey guys, some of you may remember me posting questions about problems with a fuel gauge or sending unit on my '72 GMC. Not a stovebolt, but still a GM. Anyway, all of the replies based on the tests I did at the time were that it couldn't be the fuel gauge. After replacing the sending unit for the 4th time still with no reading on the gauge, I ended up buying a new gauge, another new sending unit, a printed circuit and and new sending unit wire. Turns out it was the gauge after all or possibly the resistor that was mounted on the back of the early model gauges. The gauge appears to be reading accurately, but a new problem arose and I wanted to see if any of you have ever experienced it or have a possible solution. The gauge when it came from the factory was in the 4:00 position which is two times past the full mark. When I turned the ignition key on after installation, the gauge dropped back to almost a half tank which is the level of the fuel in the tank at the time. I went down and gassed the truck and the gauge read full. However, when I turn off the ignition, the gauge goes back to the 4:00 position rather than staying on full or dropping back to empty. I'll monitor the gauge as I drive it and see if it stays accurate to the level in the tank, but I'm stumped as to why the resting position of the gauge when the ignition is turned off is going to 4:00. Any ideas? While I'm at it, I wanted to mention that my experience with changing the sending units was that each time I changed the unit and the float, the new float had one or more pin holes in the brass floats. That's why the gauge would drop back to empty within 24 hours from its improper reading during the change outs. I went to NAPA and ordered a float that fits the sending units (also works with my '53 Chev pickup) and is not brass. It is some sort of solid material like plastic and resist gasoline. Since it is solid, it can't develop a pin hole. I was told that the new brass floats have pin holes as often as not, so if any of you are experiencing that type of problem, this solution is worth considering. Cost me about $10. Anyway, let me know if you have any ideas about the gauge going to 4:00. Fulle on this gauge is at about 2:00. I tried disconnecting the sending unit wire and grounding it. The gauge returns to empty when I turn on the ignition like it is supposed to. But when I reconnect, it goes past full and all the way to 4:00 again.
