Greetings and salutations listees. Since my last post with questions on the
charcoal canister and vent valve I got several replies from Dennis and others;
 all of which are much appreciated. I also researched the Vanagon.com
archives  and checked Bentley. I decided to test the valve per Bentley (works
correctly) and then proceeded to remove the charcoal canister (worth the 5  minutes
it takes IMHO). I then tapped, rapped and applied various percussive
persuasion to the canister until air passed through from the bottom to the top  with
much less resistance. You can beat on it with discretion as it is not metal
and will not dent but do exercise some prudence as the canister is plastic  and
may crack if too much force is applied. My van has 245k and nothing has  ever
been touched with this area of the emissions components so I was  pleasantly
surprised at the fine condition of the canister. The valve is only  inches
from the canister BTW-another question that I had. The end result was  after
running the engine for over one hr. and then shutting it off, the  tank did not
de-pressurize or make the "donk" sound after about 15-20  seconds as it did
before. I also removed the fuel cap and did not hear the  "whoosh" sound. I know
now that my tank is air-tight after replacing all of  the lines and grommets
and that the seal on the gas cap is good based on the  pressurization symptoms
that I experienced. After correcting the clogged  canister issues the engine
seemed to have better acceleration and  performance. Maybe this is
"psychomechanical wishful thinking" or  maybe the fuel pump has better fuel delivery along
with the fuel pressure  regulator working more efficiently. The fuel pump it
would seem,  should have better operating pressure as not having to work
against the  vacuum created in the tank. Synopsis: if you are hearing your  tank
depressurize 15-30 seconds after shutting off your engine, take  the time to
check your canister vent valve and the canister for proper flow. If  either cannot
be corrected replace one or both as needed. It would seem to  reason that not
doing so could indirectly effect fuel flow to the  injectors and put
additional strain on the fuel pump. A fuel pump costs  around $195.00 and a new
canister and vent valve from Van Cafe is  about $108.00. If my logic on the benefits
and possible failures is flawed here,  will someone with more knowledge and
experience correct any disinformation  disseminated to the list from this post?
As always, your results (YMMV) may vary  but it works for me.

David Clarkson
90 Westy (245k-getting fuel with much less effort now it  seems)

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