Fuel pump help

[E. Roy Wendell IV]

>
> Message: 10
> Date: Thu, 08 Sep 2005 07:01:14 -0400
> From: Kneale Brownson <kneale at coslink.net>
> Subject: Re: Fuel pump help
> To: Michael McLaughlin <mcloffs at mac.com>, quattro at audifans.com
> Message-ID: <4.1.20050908065723.010c0678 at pop.powerc.net>
> Content-Type: text/plain; charset="us-ascii"
>
> I've had fuel pumps fail in a somewhat intermittent manner.  That is, 
> car
> wouldn't start but some time later it would on two or three occasions 
> and
> then the pump wouldn't run at all.  Wouldn't run when removed and 
> connected
> directly to a battery.
>
> At 09:53 PM 9/7/2005 -0700, Michael McLaughlin wrote:
>> Hi everyone. Recently my girlfriend's 1995 90 Quattro died on the
>> highway and today I did some troubleshooting. There's spark, so I 
>> moved
>> to the fuel system. I jumped the fuel pump relay and it didn't make 
>> any
>> difference, so I then moved to the fuel pump. It wasn't making any
>> noise so I took off the cover in the trunk and got to work with the
>> multimeter; it's getting power but the pump isn't doing anything. This
>> leads me to believe the pump is dead.
>>
>> One funny thing happened, though. When testing things today twice the
>> car started, ran for about 10 seconds and then died again. Both times
>> it sounded like there was activity at the pump but then it quit. Does
>> this change anything?
>>
>> Anyway, assuming my diagnosis is correct, is replacing the pump
>> some

Sounds like the normal mode of failure for worn out brushes on the pump 
motor. The brushes get worn to the point that they are too short for 
the springs to keep them in proper contact with the commutator. I had 
one on a BMW 318 once that I kept going for a couple of months by 
smacking the pump with a small hammer every time it refused to run 
(external pump). After finally replacing the pump I cut the old one 
open and verified the worn brush theory. Very educational experience to 
cut apart these little mystery devices. Theory and diagrams are cool 
but don't compare to actually laying hands on all the little bits.

Roy Wendell
Morgantown WV, USA
turbo quattro type 44 times 3