Date:         Tue, 7 Dec 2010 10:46:34 -0600
Reply-To:     John Rodgers <inua@CHARTER.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Rodgers <inua@CHARTER.NET>
Subject:      Re: MAF Sensors and the Vanagon
Comments: To: Larry Alofs <lalofs@GMAIL.COM>
In-Reply-To:  <AANLkTimzaNfWpZiMUZ5jgduyELcxes8eJCXQq3g30Leg@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 12/7/2010 6:41 AM, Larry Alofs wrote:
> It has been my impression that the accelerator pump in a carbureted
> system is, in part, designed to cope with the loss of vacuum when the
> driver steps on the gas suddenly.  Less vacuum means less gas being
> sucked thru the jets.
>
> Larry A.
Larry, you are exactly correct - almost.

When one puts the pedal to the metal, the opening of the butterfly valve
in the carburetor throat permits more air through it. In that moment of
time, there is a lag in fuel flow  and with increased air flowing
through the carburetor the  fuel mixture suddenly goes lean, even to the
point of stalling the engine.  To compensate for this, the engineers
have added a device called an accelerator pump. It is designed to give a
squirt of raw fuel directly into the throat of the carburetor thereby
giving an additional charge of fuel to the mixture so as to prevent the
stalling of the engine when the butterfly opens suddenly.

Just my $0.02.

Regards,

John

.


John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com