Date:         Fri, 11 May 2001 23:26:58 EDT
Reply-To:     Wolfvan88@aol.com
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Lilley <Wolfvan88@aol.com>
Subject:      Re: Fuel Regulator pt 1 of 3
Comments: To: dbeierl@attglobal.net
Content-Type:  multipart/alternative;

Bosch: Line "when the fuel pump comes on...The higher the pressure, the more
the diaphragm moves away from the return pipe..."

It is in error.  The pressure is dependent on the restriction to flow
throughout the return line.  I put an electric fuel pump on my 73 VW Bus.  I
swapped the single outlet stock fuel tank with a dual inlet and outlet tank
from a 76' Bus.  I ran the line from the tank to a T fitting, to each carb,
then to another T fitting then back to the tank return.  Well, tried to fire
it up and it would not run.  The pump was set for 3 psi, for carbs, but the
engine would not run until I put a restriction into the return line.
Pressure is built by restriction.


The stock pump can go to 100 psi+ in pressure But only if there is a
restriction that forces the pump to use ALL of it power to force fuel through
an opening to obtain that pressure.

On my adjustable fuel pressure regulator, I get pressure by turning a screw
that compresses the spring in the FPR closing the opening, increasing the
restriction to flow, thereby increasing the pressure.

It is the fuel pressure regulator that determines the initial pressure that
then is acted upon by the manifold pressures, not the pump.  The pump just
uses as much pump power to flow fuel as the regulator allows.

Robert

[text/html]