It is common for the screen on the bottom of the canister to rust out and
allow the carbon to fall out and clog the vent inlet. The vacuum operated
should open when the throttle is opened. If the system is working
normally, it will be common for pressure to let out when the cap is
removed. It should pressurize but never go into vacuum. Vacuum can
collapse a tank, especially the aftermarket ones.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David Clarkson
Sent: Friday, November 09, 2007 10:56 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Charcoal cannister/valve problems

I believe that I have problems with either my charcoal canister or valve.
The tank has a "donk" sound shortly after shutting off the engine when it
is
probably depressurizing. I also here a whoosh sound when removing the fuel
cap.
I had an earlier post on this and one member suggested checking the vacuum
line  that came from the fuel pressure regulator. This is in good
condition.
Does  anyone have any way of testing the canister? Bentley has some basics
on
testing  the valve (which I have yet to locate). I am also a bit confused
as the
bottom  of the canister should lead to the air cleaner housing (a right
angle
fitting on  the top with a hose going to the canister). My vehicle does
not
have this hose  coming from the fitting. Anyone have any ideas on testing
or
where the valve is  located or other possible locations for this hose that
Bentley says should go to  the air cleaner housing? Thanks.

David Clarkson
90 Westy (244k)

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