Matt,

I found that old listing, and now I know what you mean by "high". To summarize what I think I read, you ran two 3/8" fill vent lines to the front and up into the space behind the interior panel that covers the plumbing for the fuel filler neck. And then you teed them into a half-inch hose right below where the half-inch hose fits on the filler neck.

And the reason is that the main tanks fills first--the flow from the gas pump pushes fuel into the rear tank before doing much filling of the front tank, and when full it blasts a shot of gasoline into the fill-vent tubing before much fuel enters the front tank. With the TEE in the rear, that blast of fuel blocks air flow in the vent from the front tank, forcing the front tank to fill very slowly and unhappily. So, the first 25 goes in easy, and the second 25 doesn't. With the TEE in the front and right under the filler neck, that blast of fuel doesn't make it into the fill vent for the front tank, and it can vent as it fills as it should. The usual
practice of filling on the slow setting is a partial solution because it makes it easier for the tanks to equalize a bit as they fill--there isn't quite as much dynamic flow pushing past the side opening into the front tank.

Did I get that right?

I'll do this in the future--don't have to drop the tanks to do it and I can manage this one in my driveway.

Rick "who'll probably get a response to this in person in Elkhart, assuming everything goes together well tomorrow" Denney