1972 Fuel Transfer Valve

[PbFut]

The return line is on later (I don't know for sure, may have started in 1970) fuel pumps. The return line was a regulator allowing surplus pumped fuel a way to return back to the fuel tank. It helped with vapor lock and likely provided a more reliable pressure regulation method for carburetor supply between pump and carb. The valve you have only directs the supply fuel. Left, right and main tank is the upper 3, and the center elbowed nipple goes to the fuel pump. If your truck has the return style pump, that line is directed back to the main tank and has no provision to return to either of the auxiliary tanks. Say you fill all 3 tanks. If you start drawing from an aux tank, the return fuel will overfill the main tank and you will have fuel pushing out the gas cap. So you start drawing from the main tank. When low, switch to 1 aux tank. You will actually see the main tank gauge come up as the return fuel is pushed to the main. Draw the main tank down again, then switch to the 2nd aux tank a repeat. It was sort of a pain to deal with, but better than stopping every 175 miles or so. I corrected using 2 modern electric valves. A good 3 tank selector valve with return line ability is very pricey. The modern electric valves available on amazon Controls...Supply, return, pump power if intank, and sender signal. So with one flip of a switch all points are covered and no out of sync gauges or return lines. I did a post on it a while back detailing the setup. It's involved but nice to use when complete. There were a few of us messing with the aux tanks about 3 years ago. Lots of posts on the subject then it quieted down as we all got things completed. Remember, old fuel tanks are dangerous. The vapers inside can last for years and create a large bomb.