Date:         Sun, 28 Jun 2009 15:41:02 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Fuel Filter "Update" Results
Comments: To: Keith Hughes <keithahughes@Q.COM>
In-Reply-To:  <BLU0-SMTP479A4D7D9081BE0FC0BC94DA330@phx.gbl>
Content-Type: text/plain; charset="us-ascii"; format=flowed

Keith, I agree with everything you say from the technical side, but
have a few quibbles from the practical side...
At 03:20 PM 6/28/2009, Keith Hughes wrote:
>>So, is it fair to say that a noisy FP may be caused by the pump delivering
>>too much volume?
>No it isn't.  Cavitation *reduces* the liquid volume being pumped.

If you understand Dave's statement as implying "too much output [for
the current inlet conditions to deliver without exceeding the maximum
suction head]" then it makes sense.

>being high enough to create gasoline vapor bubbles (not "vacuum"
>bubbles - ain't no such critter in a fluid system),

Vacuum is a relative thing in our earthbound existence -- I submit
that if there's a small enough amount of vapor that the bubbles can
collapse violently with noise and destructive potential, that calling
them vacuum bubbles informally is quite legitimate.

>Wrong approach - you need to fix the actual problem which is a suction
>side flow restriction

Agree in principle.  However when you have a threshold cavitation
problem that's not fixed by removing the inlet filter, I think
slowing the pump could potentially put off more serious repairs for a
long time.

>you are now.  Slow it enough so that the regulator can't maintain 45psi

C'mon, Keith, clearly nothing I've suggested contemplates cutting the
pump output in half, quite the reverse.  :-)

Cheers,
David

  --
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"