[urq] Warning about Fuel Pressure Accum.
Ben Swann
benswann at comcast.net
Thu Jan 29 11:59:00 EST 2004
Bill,
Sorry for the delayed reply. You are correct - I don't know about part number, but the external fuel pressure regulators are on both implementations - CIS and CIS-E&E3. The Warm Up Regulator has been sometimes called Control Pressure Regulator on earlier CIS cars, as it regulates control pressure with respect to manifold vacuum/pressure as well as temperature. The later versions found in '86 on 5kts only did temperature, excepting there is a port to provide for deviation in atmosheric pressure.
The other regulator I was referring to is internal to the fuel distributor and consists of spring, plunger and o-rings. As I under stand it also regulates, but in this case system pressure on one side is fed to the control pressure and I think the valve is called a system pressure regulators, as other side is fed to the warmup pressure regulator. I don't know what if anything serves this function in CIS-E systems, as the warmup regulator is functionally replaced by the DPR and there is no WUR on CIS-E.
I think was you call EHA I am calling a DPR(differential pressure regulator). What I am calling Fuel Pressure regulator is the Zinc Chr. Plated Cyl. you mention, and I have for the time ruled this out as you mention failure IMO is rare, but that was one of the questions I had asked.
I am stating all this from memory, so really, one needs to study the diagrams in Probst or other showing the the different CIS variants.
Ben
----- Original Message -----
From: Bill Bennett
To: Ben Swann ; Patrick Carlier ; SpotatAshleys
Cc: urq at audifans.com ; quattroguy83 at yahoo.com ; quattro at audifans.com
Sent: Wednesday, January 28, 2004 11:31 PM
Subject: Re: [urq] Warning about Fuel Pressure Accum.
oversimplification of course,, umm Ben, could you explain the difference between a control pressure regulator and a warm up regulator? they seem to bolted onto the same place on my 3 CIS cars. my impression is they are the same component. and on CIS-E the pressure regulator is the zinc chromate plated cylinder with three fuel fittings next to the fuel distributor (rare failure) and the EHA grey plastic thang bolted to the fuel distributor (common failure is external fuel leakage for it) Bill
----- Original Message -----
From: Ben Swann
To: Patrick Carlier ; SpotatAshleys
Cc: urq at audifans.com ; quattroguy83 at yahoo.com ; quattro at audifans.com
Sent: Wednesday, January 28, 2004 6:19 PM
Subject: Re: [urq] Warning about Fuel Pressure Accum.
Note - not in all cases will simply turning the key on enable the fuel pump
relay. To really do this one must jumper the relay contacts. 30 - 87
AFAIR - the larger contacts which can be bridged with a wire at least 14
Guage with spade lugs on both ends.
I agree that if charging the system up by running fuel pump and then engine
starts promptly, then there is a likely leakdown system pressure side of the
fuel distributor. Essentially from the fuel pump to the plunger portion of
the fuel distributor - oversimplification of course..and don't forget about
the control pressure regulator - not the warmup regulator, which can also be
a problem.
Ben
----- Original Message -----
From: "Patrick Carlier" <p.carlier at pandora.be>
To: "SpotatAshleys" <spotatashleys at hotmail.com>; "Ben Swann"
<benswann at comcast.net>
Cc: <urq at audifans.com>; <quattroguy83 at yahoo.com>; <quattro at audifans.com>
Sent: Wednesday, January 28, 2004 4:20 PM
Subject: Re: [urq] Warning about Fuel Pressure Accum.
> Keith , have you tried this :
>
> Turn on the ign key , but don't crank .
> You should be able to hear the the fuel pump running for a few seconds .
> Repeat this several times in a row : allow the pump to run till it
switches
> of ,
> switch off the ign and turn the pump back on .
> This will allow you to build up pressure on the fuel system .
>
> If after that the car starts normal or much better , you have either a
> leaking check valve
> or a broken accumulator .
>
> Pat
>
>
> ----- Original Message -----
> From: "SpotatAshleys" <spotatashleys at hotmail.com>
> To: "Ben Swann" <benswann at comcast.net>
> Cc: <urq at audifans.com>; <quattroguy83 at yahoo.com>; <quattro at audifans.com>
> Sent: Wednesday, January 28, 2004 8:59 PM
> Subject: Re: [urq] Warning about Fuel Pressure Accum.
>
>
> > Thanks Ben (and others too)
> > In an effort to cure the long cranking I replaced all the injectors
first
> > but still have the problem hence my questions now about the accumulator.
> The
> > battery is brand new and very good. It always starts (so far) but after
an
> > inordinate time cranking.
> > It looks like keep replacing things till it starts properly and the
> > accumulator could be next unless someone has a bright idea.
> > Thanks again
> >
> > Keith
> >
> > '87 WR
> > ----- Original Message -----
> > From: "Ben Swann" <benswann at comcast.net>
> > To: <ashleyj.cobain at virgin.net>
> > Cc: <urq at audifans.com>; <quattroguy83 at yahoo.com>; <quattro at audifans.com>
> > Sent: Wednesday, January 28, 2004 5:27 PM
> > Subject: [urq] Warning about Fuel Pressure Accum.
> >
> >
> > As you mention, when operating correctly, the accumulator should help
> > maintain the fuel pressure to around 35 PSI after shutoff if there are
no
> > leaks in the system.
> >
> > The FP accumulator also act as a damper to smooth out pulses/spikes in
the
> > pressure. Analogous to the vertical tube a plumber would install to
> prevent
> > water hammer when a faucett is closed rapidly in a plumbing system, but
> also
> > similar to the water pressure accumulator used on well fed systems - a
> tank
> > that holds water with a bladder full of air at the top. The accumulator
> on
> > the fuel injection system uses a spring instead of air to maintain this
> > pressure.
> >
> > As you allude to a faulty pressure accumulator can cause hard starting,
> long
> > cranking. I have found more often, a leakdown on the injector side of
the
> > system is the problem, and the accumulator is secondary.
> >
> > Ben
> >
> > [Please excuse my ignorance but what is the precise function of the fuel
> > accumulator?
> > It is supposed to maintain system pressure when the engine switched off?
> In
> > other words could this be my problem with cold starts? Hot starts are
> fine.
> > Mixture is not a problem during cold starts, once started. The warm up
> > regulator is working because the air fuel meter shows it is doing it's
> job.
> > The problem is that I have to crank it lots before it fires. Is this
> because
> > it has lost system pressure over night and I then have to crank for fuel
> > pump to restore pressure?
> >
> > Look forward to receiving your thoughts
> >
> > Keith
> >
> > '87 WR]
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