re
"should be larger (as later model year tanks are) to
meet demands of this increased fuel use?'

I hastled with this once. I replace a fuel tank in a late 2WD vanagon ......
and the old tank had the larger fuel outlet ..........( 7/16 inch, OD,
approx )
and the replacement new tank had the smaller outlet.........about 5/16 inch.

that particular van had a DOHC 2.5 165 hp subaru engine I had put into it
......
and that engine liked to go right to 4,200 rpm and just stop winding out at
that rpm.
We were pretty sure it was due to lack of a proper Vehicle Speed Sensor ( it
was , in the end )
but we wondered if it was that fuel outlet size causing the issue.
It wasn't .
I don't think a 4 cylinder vw engine can digest more fuel than that small
size opening and the fuel pump can deliver.
scott
www.turbovans.com

----- Original Message -----
From: "neil N" <musomuso@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, June 27, 2009 11:08 AM
Subject: Re: Fuel Filter "Update" Results

> On Sat, Jun 27, 2009 at 10:41 AM, David Beierl<dbeierl@attglobal.net>
> wrote:
>> ......
>
>> If anything, flow would be reduced when the engine is working, since MAP
>> would rise causing a corresponding rise in regulated fuel pressure.
>
>
> Thanks David.
>
> Ok, so I had to google MAP....  :)
>
> I'm sure I could google these principles, but if you or someone has the
> time....
>
> Assuming:
>
> at higher engine RPM's, (intake) manifold absolute pressure rises,
> more vacuum applied to diaphragm side of FPR, more fuel "allowed" into
> fuel rail, more fuel used.
>
> Does this mean that the increased demand on what we assume is a
> constant rate of fuel flow, "pushes" ID of tank outlet past it's
> limits? i.e. ID should be larger (as later model year tanks are) to
> meet demands of this increased fuel use?
>
>
> 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