Originally Posted by pdallas
My 1984 310 has a 40 gal fuel tank. For some reason it has 4 fuel lines: one to fuel pump, one return, one to generator, and one that is just there. I discovered the fourth line when I filled the tank to capacity, it overflowed onto the ground. Not the most pleasant thing to occur at a fuel stop. Does anyone have any idea what's was the intended use for the extra line. Can I simply plug the line?
I can't speak for sure about your tank but on mine which is 60 gal and a diesel there are several spare ports on top of the tank. I guess they put extras in for more than one application.
I too found the existence of an open port the first time I filled the tank. I dropped the tank and there are two ports with pick up tubes and several return/vent ports. One unused port had a 90 degree elbow and no plug. I don't recall how the vent was set up, fading memory, but I brazed an elbow in the filler tube near the top and ran a hose from the open elbow. I thought it might help vent some air and foam during fill up.