> Date:    Sun, 28 Jun 2009 10:33:30 -0300
> From:    Dave Arthur <dave.arthur@NSCC.CA>
> Subject: Re: Fuel Filter "Update" Results
>
> 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.  The
reason you have cavitation is that you are running at or below what's
called the "net positive suction head" value for the pump.  Lowering the
suction side pressure below that limit results in the vapor pressure
being high enough to create gasoline vapor bubbles (not "vacuum"
bubbles - ain't no such critter in a fluid system), and while the
bubbles do collapse back to liquid on the discharge side, the net effect
is less flow with of course lower discharge pressure.

> Does the list have any advice on what resistance to use or
> what wattage has been used to 'slow' down the pump?
>
Wrong approach - you need to fix the actual problem which is a suction
side flow restriction (unless you've installed a different FP than the
OEM version).  If there's enough crap floating in the tank to keep
clogging filters or the tank outlet, you need to pull the tank and clean
it out (or replace it).  Slowing the pump down might mask the problem
until you get even more restrictions, but then you'll be back to where
you are now.  Slow it enough so that the regulator can't maintain 45psi
and you'll start getting mixture issues, since the fuel map
(rpm/injector pulse frequency) is calculated for a specific pressure range.

Keith Hughes
'86 Westy Tiico (Marvin)