No Flow through Pressure Regulator

[Marc Boucher]

Using a high-end bicycle pump I was able to more or less test the regulator.
It is working correctly.  At a set pressure it opens and lets air pass.
Based on the pressure gauge built into the pump the best estimate of opening
pressure is between 75 and 80 psi.

It would seem easy to conclude that the fuel pump is the problem except for
a few facts:

1.) Last week when I began this testing, the pump was producing enough
pressure to cause return flow.
2.) Throughout all the testing, I have yet to get any fuel to flow through
the top of the fuel distributor.  i.e., I have unscrewed each line to each
of the 5 injectors.  I understand that it requires high pressure to fire an
injector, but even with a moderate amount of pressure, shouldn't there be a
flow out of the fuel distributor nozzle (assuming the plate is lifted and
the line to the injector is unscrewed) ?

Tomorrow I will reinstall the regulator and see one more time if I don't get
return flow.  There are 3 things that I want to check that might have
changed since last week and would impact the fuel pump's ability to pump
a.) the state of the battery...I took it off the trickle charger last week
and with all its been through lately...
b.) the wire I'm using to 'jumper' the relay...this week I hooked up a long
wire so I could be on the other side of the car...it is relatively thin wire
(a single strand of cat5 wire) so this could impact

Last week I also conducted a flow test as had been noted.  60ml was
collected in a period of between 1 and 2 seconds.  Taking the worst case
gives 30ml/second or 900ml in 30 seconds.  I'll try and repeat this tomorrow
and measure a full 30 seconds worth, if conditions are a bit safer.

Marc

----- Original Message ----- 
From: "SJ" <syljay at optonline.net>
To: <quattro at audifans.com>
Cc: "Marc Boucher" <mboucher70 at hotmail.com>
Sent: Wednesday, February 04, 2004 10:37 PM
Subject: Re: No Flow through Pressure Regulator


Sounds like a bad fuel pump to me. If the fuel pump is not putting out
enough pressure, the pressure regulator acts as a closed valve. System
pressure is around 90 lbs. If the pump only puts out 80 lbs, the pressure
regulator wont open . . . no fuel flow thru it.

If you had an air compressor, set it to 100 lbs, blow air into the input
opening . . .air will rush out the other end. Set air compressor to 75 lbs,
no air will travel thru the regulator. This is a quick check if you have
access to air compressor.

Since you have it all apart, why not try the fuel pump flow test? The test
may not be valid because the pump isnt fighting against the pressure
regulator. But, the test is easy to do.
You should get at least 750 cc in 30 seconds. Use the tables that I sent you
for more accurate figures.


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q


> From: "Marc Boucher" <mboucher70 at hotmail.com>
>
> Today's update:
>
> 1.) Cleaned the DPR thoroughly...found a plastic hose that fit snugly into
> one hold of the DPR and can confirm that there is clear passage through
the
> DPR...i.e. it is not clogged.
>
> 2.) Energized fuel pump, saw fuel flowing out one of the holes from the
fuel
> distributor that goes to the DPR.
> 3.) Reattached DPR.
> 4.) Detached return hose.
> 5.) Energized fuel pump.  Same result as before.  No output from return
> hose..Pump slows to a crawl as pressure builds up with no where to go.
> 6.) Detached, small pipe at the pressure regulator.  Energized fuel pump.
> Confirmed flow out of pipe.
> 7.) Reattached small pipe and detached thicker pipe at the pressure
> regulator.  Energized fuel pump.  Confirmed flow out of pipe.
>
> Thus fuel distributor and both lines that flow into the pressure regulator
> are flowing but nothing is coming out of pressure regulator.  Thus either
> the pressure regulator is clogged or bad, or the fuel pump isn't pumping
> sufficient pressure or both.
>
> I've filled the pressure regulator with carb cleaner and have it sitting
in
> a sealed glass container.  I'll leave it soaking overnight and reattach
> tomorrow.  Someone mentioned that they had an adjustment screw.  This one
> does not.  And its the only part that I've seen that doesn't have "Bosch"
> (or any other brand) stamped on it.  One end attaches to a plastic hose
that
> leads to a large container near the right fender.  I assume that fills
with
> air in order to keep pressure when the car is shut off?  I'm assuming
> there's no benefit to filling that end of the regulator with carb cleaner.
>
> Marc