system pressure leakdown

[Ben Swann]

I disassembled the Warmup/Fuel Pressure Regulator(FPR) and cleaned the
metal diaphram - it really didn't look bad.  Back together, made maybe a
little difference.

Part of the problem that crept into the works was actually my guage set
misbehaving.  That must have happened right about the time I put new
o-rings in the check valve.  Anyway, swapped check valves between the two
avants with no difference in either car, so I rule that out.  Pulled the
guages out, and was able to get the car to idle fine when adjusted slightly
rich, such that the frequency valve is not activating at idle.  So the
guages were messing me up, causing me to think I did something wrong when I
replaced the o-rings in the check valve.

Now, however, it seems to fall flat around 4000-5000 RPM - was pulling
easily to 6500 the other day, just started and idled poorly.

So the problems I still have  are:
1) Poor starting  cold and even after setting 10 min.
2) Loss of power as if mixture is off.  Sometimes it pulls great, and
sometime it doesn't.

I am still pretty sure the problem is in the fuel delivery.  I guess I need
some new guages, and to re-test.  Perhaps swapping the Warmup/FPR with the
other car will rule that in or out.

Anyway, the car runs OK enough to use, but I'm troubled now, after all of
this work so far.

Ben

On Tuesday, April 16, 2002 1:07 PM, Ben Swann
[SMTP:bswann at worldnet.att.net] wrote:
> 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.
>
>