system pressure leakdown

[Jon Boyer]

On other CIS cars (VW) I have seen the return line damaged where it runs
along the underbody.  It is a rather stout steel line, but sloppy jack work
can damge them.  I have tried with little success to clean out WU
regulators.  Other areas to check is the check valve located at the fuel
pump and the fuel pressure accumulator.

good luck
JB


>From: Ben Swann <bswann at worldnet.att.net>
>Reply-To: "bswann at worldnet.att.net" <bswann at worldnet.att.net>
>To: 'Graham Thackrah' <gthack at geog.ucl.ac.uk>
>CC: "'quattro at audifans.com'" <quattro at audifans.com>,
>"'quattro at isham-research.com'" <quattro at isham-research.com>
>Subject: RE: system pressure leakdown
>Date: Tue, 16 Apr 2002 13:06:45 -0400
>
>Graham.,
>
>No, not too late as I am still having problems.
>
>Perhaps total leakdown both control and system sides is normal, but there
>was something seemingly flaky going on with the control pressure.
>
>I wanted to verify system check valve not leaking, which Probst alludes to
>checking first.
>I put all new O-rings on the system pressure regulator check valve.  Did
>this 2X because I had gotten the inner and outer mixed up the first time,
>ruining the outer.
>
>Now I get about 85%system pressure(was 90 PSI) on both sides(same with the
>correct o-ring placement as with the previous botched job), so I attribute
>this to something I did wrong, but can't figure what exactly.  The outer
>O-ring is a sloppy fit and tends to slip out of the seat on the shaft when
>inserted.  Anyway, now  I am sure the correct o-rings in the right spot,
>but it is screwed up worse than before I touched the check valve.
>
>Maybe the system is totally blocked now at the c.p. regulator. Pump on ->
>system pressure.  When the pump is off,  pressure still equal on both sides
>and drops to about 50 PSI.
>
>I am going to check the screens on the c.p. regulator this afternoon.  How
>much insanity is disassembling and cleaning it.
>
>Probst also suggests a blocked return line.  where might it get blocked?
>
>What else should I be looking at?
>
>Thanks for the support!
>
>Ben
>
>On Tuesday, April 16, 2002 6:02 AM, Graham Thackrah
>[SMTP:gthack at geog.ucl.ac.uk] wrote:
> > Hello Ben,
> >
> > Sorry if this is a bit late, I took a look through Probst's FI book and
>it
> > shows a plot in there with system pressure rapidly falling to c. 3 bar
> > after shutdown, which it is supposed to hold for a few hours, but then
>SP
> > drops off to zero after a prolonged period of time "through various
>minor
> > leaks in the fuel system." I'm not sure if total leakdown overnight is
> > undefined behaviour for CIS systems. One place it did say to check on
>CIS
> > systems suffering fast leakdown is the system pressure regulator, it has
>2
> > O rings in it and you can buy a kit from the dealer with new ones in.
>
>Right I just got 2 kits today.  Used/abused the one I had last week.  Of
>course the Bently blowup does not show detail, and the kit has no
>instructions.  Almost lost that tiny c-clip that retains the shaft which
>has the outer(control pressure?).
>
> > Dodgy O rings in there could cause both control and system pressure
> > leakdown, one O ring seals off the return from the CPR and the other
> > system pressure return to the tank.
> >
> > hth,
> >
> > Cheerio,
> >
> > Graham.
> >
> > P.S. just in case - and sorry if this is teaching you to suck eggs! -
>but
> > when testing cold control pressure you did disconnect the CPR heater
> > didn't you?
>
>Yes
>
>  I got that wrong a few times when I was checking my own car
> > out but I think if you jumper the FP relay it also sends a feed to the
>CPR
> > heater so you'll be testing warm CPR operation even though the engine is
> > not running.
>
>


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