Also make sure the vent valve is connected and opens when the throttle is
opened. This valve is located in front of the firewall near the air filter.
There should be a control hose connected to the throttle housing. You can
usually hear the valve open as the throttle is opened.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Steve Williams
Sent: Thursday, September 29, 2011 10:18 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Post gas tank/system reseal - vacuum in gas tank

Hi,

Obviously my gas tank reseal and replacement of gas lines is working great
because now my gas tank builds up a vacuum while I'm driving.

When I stop, at some point afterwards I get a large thunk as it pops back
into shape.  If I take the gas cap off shortly after driving (eg:
to put gas in it), a large hiss and thunk as the vacuum is broken.

Going through the "Green Bible", about the only thing i can see that should
be "venting" the gas tank is the charcoal cannister?  Does this sound right?

Do these charcoal cannisters get plugged?

I have no idea where to go from here :-(

I guess it's a good problem to have compared to gasoline flowing onto the
ground when filling the tank :-)

Thanks!
Steve Williams
(the other one ;-)

1991 2.1 Westfalia