Be very careful around gasoline, John...

But there are several vents,lines, etc on top of the vanagon gas tank.

I had a similar problem when I  bought my vanagon (used). Gas would
dribble out of the top, and I couldn't fill the tank.

The tank is not rectangular, but has two bulges (left and right side).  On
top of these bulges are plastic T-fittings that press fit into rubber
grommets - my grommets were bad, and one fitting was broken.

I found some rubber grommets that were a good fit at a hardware store, and
some T-fittings at the auto parts place.  Not OEM parts, but they work.  No
leaks in 8 years.

You need to lower the rear end of the tank to get access to things, and
even then the space is tight.  Be patient, and you can get it done in a few
hours.
I didn't drain my tank.

Please, be careful around that gas tank...

John Hung
Auburn, AL
84 GL