Tip #6 Holy crap, there is gas spilling out of my Vanagon!
The problem that you are experiencing has to do with the vapor control system on Vanagon fuel tanks. The fuel tank on all 2WD Vanagons has kind of an inverted saddle shape to it. The tank is high on both sides, and has a depression down the middle. Interestingly, the depression down the middle was put there to allow the hot air duct to pass from rear to front on air cooled Vanagons. Even though there is no purpose for it now, and even though 90% of all Vanagons ever produced were water-cooled, the fuel tank design never changed. Go figure….
The filler neck is fitted on the passenger side, at the top of one of the tall sides of the fuel tank. In order for fuel to fill up evenly on both sides of the fuel tank depressed area, VW came up with a somewhat elaborate way of venting the fuel vapor. The system is comprised of a transfer tube assembly, three grommets, and about a meter or so of 5mm fuel hose. There is also a grommet around where the filler neck enters the fuel tank. The system is good until the grommets dry up, or one end of one of the fuel hoses cracks and/or comes off. Then, the next time you fill up, N-I-A-G-R-A!
Check out the red star areas in the photo below. That’s a leaker!
Ten to fifteen years is what you could expect from the system between overhauls, until MTBE was introduced. After MTBE was introduced in California, the system was good for as little as two years. Vanagons were not the only vehicles adversely affected by the introduction of MTBE. Most gasoline vehicles experienced some sort of fuel system/vapor control system failure, and most were many times more expensive to repair than a Vanagon.
The fix on a Vanagon is to drop the fuel tank, replace all the hoses and grommets, and put it back up into place. For an experienced Vanagon shop with all the proper tools and parts, it takes about four hours. For an individual without experience, it’s typically a 5-7 hour job, plus the parts.
Keep the faith. And don’t forget, NO SMOKING!