Re: Fuel pump roulette - part duex

[QSHIPQ@aol.com]

In a message dated 97-10-18 06:27:44 EDT, you write:

> Whoops, that was me ;-)
Never name names, me always say.
 
 >Scott --when the FP fails-- what happens that is able to get past the fuel
 >filter and cause damage to: (1) fuel head, (2) injectors, (3) fuel
 >regulator, etc? I understand crapping up the fuel tank, and I don't say the
 >rest _doesn't_ happen, but why? Seems the FP decomposes into microscopic
 >pieces that pass right through the filter?
Don't give that filter too much credit.  Things can get thru it.  Remember,
you have system pressure at 70psi plus, that can literally push stuff thru
the filter, especially if it's already "full".  I have seen some pretty big
pieces of material in the head unit on occasion, much larger than a pinhead
some.  The FP decomposes into a lot of plastic and metal pieces parts, NOT
microscopic.
 
 Also, does Audi recommend permanent removal of the FP lower screen? Not
 cleaning, or replacing with a new one? I assume the problem is that the
 screen clogs up with crud from the fuel tank(?) If so, won't that stuff
 continue to cause a problem--somewhere else?
>>  Amazingly not really, a change of the FF and some techron seems to do the
trick well.  When I did the last one, the tank looked like someone poured
sand in it.  Some rough running for the first tank, then all fine.  Yes Audi
makes that permanent.  It's really a redundant screen anyhow.  The baffle in
which the pump sits in the center of the tank has an oring for the pump, and
is screened all around the baffle.  So you still have a "screen". 
 
 >Trust your ears folks.
 
>> Easier said than done for a lot of folks. My wife, for example, has
 >>profound high-frequency hearing loss--she cannot hear our smoke alarm at 3
 >>ft! Ironically, I compensate by having extremely sensitive hearing, but
>> haven't a clue as to what a "silent" (i.e., good) Audi FP sounds like. Is
>> it desirable to evaluate the FP's sound with the engine not running?
No.  The difference is really hard to miss.  Kinda like a pissed single
worker bee vs the whole nest.  Listen to a few, contrast is pretty easy.
 
 > One that gets louder when it's hot out or under
 >certain conditions is different from one that is getting progressively
 >louder.  Also, my understanding is that a later model fuel pump (motorola I
 >believe) supercedes the Bosch one at the dealer.  This is supposed to be a
 >"better" pump design.  Also about twice the price of the good ol Bosch
unit.
 
 >>Seems like the newer pump might be money well-spent. Anyone have more info
 >>on this model?
Since this newer model is a dealer only item, I would suggest (and meant to)
that hard shopping of the bosch unit can get you two for the price of one of
the newer ones.  As a rule I find the bosches good for 120-150k, so two of
those should get the life of the car (exceptions noted).  However, those
(Jeff Goggin, FI) in hot weather climates, might consider the new pump a good
investment.  The caveat to that is, if it's NOT the FP that is the problem,
then you just doubled your diagnostic tithe.  The bosch unit with the screen
removed works fine.  Yep a little more noise when hot.  But compared to the
old electric FP's I'm used to in my race cars, even at full boil, the bosch
is a whisper in comparison.

HTH