Well, I think the way it works is the filler tube is a coaxial type device, where the fuel is supposed to flow down the plastic inner tube, and the vented air then goes up the filler tube on between the outside wall and the plastic filler tube.

There is another vent tube on the top of the tank, but that is like 1/4" diameter, and I don't think Ford planned on that being the primary vent. I did replace both of mine though when I dropped the tanks last week, those lines were in bad shape.

I still think I need to somehow remove part of the filler tube right where the nozzle goes in. It is restricted right there for several inches. Can't be a good thing!

Wayne