Date:         Mon, 26 Oct 2009 20:05:30 -0700
Reply-To:     neil n <musomuso@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         neil n <musomuso@GMAIL.COM>
Subject:      Re: Charcoal Cannister Purpose
Comments: To: David Beierl <dbeierl@attglobal.net>
In-Reply-To:  <4ae64d85.0e0bca0a.7ab4.0d44@mx.google.com>
Content-Type: text/plain; charset=ISO-8859-1

Sorry to semi-hijack this thread people.

On Mon, Oct 26, 2009 at 6:31 PM, David Beierl <dbeierl@attglobal.net> wrote:
> At 08:52 PM 10/26/2009, neil n wrote:


>> Bentley shows air cooled, Digijet, and Digifant, charcoal canister
>> bottom hose connecting to the air cleaner.



Something I just noticed. P20.3 shows *top* hose in air cooled diagram
going "To air cleaner". It doesn't show where bottom hose goes.
But.....

IIRC, (my air cleaner is long gone) on my air cooled, *both* the
larger top and bottom larger hoses from canister went to the air
cleaner. From what you're saying the top hose went to air cleaner pre
filter, the bottom hose went to air cleaner *post* filter,

This might have been part of my confusion....


>> Anyone know if the charcoal canister bottom hose on my VanaJetta
>> should be connected to the air cleaner?
>
> Yes -- any air input to the engine should be filtered



>> Since the air cleaner is sucking on this hose, is that crucial to the
>> charcoal canister operation?
>
> Other way around -- the vacuum connection direct to the intake manifold
> (through a 1.4 mm orifice) pulls filtered air from the filter box through
> the charcoal and into the engine.  The other connection through a much
> smaller orifice to the throttle body only opens the vacuum valve to allow
> this when the throttle plate opens far enough to pass the drilled hole in
> the throttle body.


Right ok. I have a solenoid actuated EVAP purge valve (cycled on/off
by ECC), but it appears to do accomplish the same thing in a similar
manner.

So it *basically* goes like this?

Excess fuel tank vapours go through a hose, into canister via top
smaller connection. At certain times, a valve opens allowing filtered
air from air cleaner to be pulled through bottom hose of charcoal
canister, through canister, out larger upper hose through the vacuum
controlled valve then into intake manifold?


Neil.

-- 
Neil Nicholson '81 VanaJetta 2.0 "Jaco"

http://tubaneil.googlepages.com/

http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines