[urq] Re. Fuel Tank Vent Update -

[Ben Swann]

Omar,

Try changing the fuel filter.  A loaded up filter will put enough back-pressure on the
pump to cause the internal check valving to divert flow to the return and a
corresponding buzz.  Other culprits are – clogged intake/pre-filter, sock or any
restriction in pump intake.  Reduced voltage to the pump might contribute.  Lastly, the
pump may be going bad, but IMO, something causes this to happen – dirt from the tank
getting into the pump  or restriction causing cavitation.  Heat will aggravate a failing
pump.

I recently chased similar noise and all of the above contributed to one degree or
another – I’m talking about different cars, pumps, layouts – internal and external pump,
but the general suggestions above apply in all cases.  In the end, often what seems like
a failing pump is generally something else – I’ve even had pumps buzz for years without
failure and buzzing occur when new pump installed and one or more of the above problems
exists.

Ben

[Date: Tue, 18 Mar 2008 10:28:56 -0700 (PDT)
From: omar millmech <h636k at yahoo.com>
Subject: Fuel Tank Vent Update-
To: Audilist <quattro at audifans.com>
Message-ID: <923414.58849.qm at web32808.mail.mud.yahoo.com>

Victim is 87 4kcsq.  Issue has been fuel pump noise. 
I've been afraid to go out of town with it, had an in-town mission & tried taking off
the gas cap to go home.  Pump was nice & quiet, unlike lately.  Got to the end of my
driveway & it got loud & stayed loud
until I shut off engine.  I spoze I'll try it again for the next in-town mission.  Could
be going-bad fuel pump + fuel tank vent.
Somewhat related- I'm not sure whether to fix it or forget it, located in Az, 1 hour
from Tucson & 2 hours from Phoenix.  Anybody know of an Audi wizard somewhere around
here?  Other side- anybody want to
make an offer?
TIA-]