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High control pressure

Started by Feather535, 12 November 2022, 09:06 PM

Feather535

Thanks.  Very similar issues in these threads.  Where did you find new o-rings for the FD pressure regulator?
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1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

raueda1

Quote from: Feather535 on 18 November 2022, 11:35 AMThanks.  Very similar issues in these threads.  Where did you find new o-rings for the FD pressure regulator?
Yes, exactly!  In this world little is every really new.  I sourced a bunch of them (minimum buy requirements) and am selling extras as kits. ;D ;D   It's outrageous how expensive new pressure regulators are considering that the only thing that can wear out is a few o-rings. PM me if interested.
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Feather535

Now I'm looking at the WUR and all the related plumbing on this 280SE.  It's hard to see under the intake manifold and even harder to access--but there appears to be another pressure regulator in the return line downstream of the WUR before it goes back to the fuel distributor.  The factor CIS manual calls it a pressure damper.  What does this thing do?  Do they ever go bad?  It looks similar to the pressure regulators in Bosch pulsed injections systems, which have been known to fail.
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

daantjie

Quote from: Feather535 on 27 November 2022, 12:10 PMNow I'm looking at the WUR and all the related plumbing on this 280SE.  It's hard to see under the intake manifold and even harder to access--but there appears to be another pressure regulator in the return line downstream of the WUR before it goes back to the fuel distributor.  The factor CIS manual calls it a pressure damper.  What does this thing do?  Do they ever go bad?  It looks similar to the pressure regulators in Bosch pulsed injections systems, which have been known to fail.

Exactly yes this is a pressure damper to smooth out fuel pulses and yes they do fail.  Best to replace but brace yourself for the price  :o
Daniel
1977 450 SEL 6.9 - Astralsilber

ramiro

As far as i know if they fail petrol will come out of the other end , i can't really believe how it could change the pressure permantly , and also when you meassure the control pressure the pressure damper is not connected normally because you are connecting the Gauge between the WUR and the Fuel Distributor.

I think that your WUR is the problem high control pressure is how the usally fail, it has a mesh filter in the inlet did you check that, worth a try before opening the WUR?


Feather535

Quote from: ramiro on 27 November 2022, 04:36 PMI think that your WUR is the problem high control pressure is how the usally fail, it has a mesh filter in the inlet did you check that,

Where is that filter?  I disconnected the hard lines from the WUR and removed the adaptors they connect to, but there is no filter there.  If it's inside the WUR, I'll probably need to remove it from the car to access it.
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

raueda1

Quote from: Feather535 on 27 November 2022, 05:15 PM
Quote from: ramiro on 27 November 2022, 04:36 PMI think that your WUR is the problem high control pressure is how the usally fail, it has a mesh filter in the inlet did you check that,

Where is that filter?  I disconnected the hard lines from the WUR and removed the adaptors they connect to, but there is no filter there.  If it's inside the WUR, I'll probably need to remove it from the car to access it.
Uhoh, now you're down the rabbit hole!  You will absolutely need to remove the WUR.  The filter is indeed inside one of the fuel line fittings, the larger of the 2 if I recall.  It's very fine mesh.  To clean it you'll need to take the damn thing apart and blow it out with carb cleaner.  This is described here someplace, best to do a search.  When you open the WUR you'll see 4 flat-head screws that need to be removed.  Be careful, they are VERY tight and hence easy to strip.  Put the WUR in a vise to do loosen them.  And handle the thin steel membranes with the utmost caution.  Cheers, 
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Feather535

Quote from: raueda1 on 27 November 2022, 07:17 PMThe filter is indeed inside one of the fuel line fittings, the larger of the 2

Just to be clear, what do you mean it's inside one of the fuel line fittings?  I removed both external fittings from the WUR (the larger one is the return) and they are just orifices-nothing inside.  Is the screen inside the WUR beneath where the fitting screws in?

On the M110 the WUR is under the intake manifold, only accessible from below.  Working under there is indeed like being in a rabbit hole...maybe worse.
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

raueda1

Quote from: Feather535 on 27 November 2022, 09:42 PM
Quote from: raueda1 on 27 November 2022, 07:17 PMThe filter is indeed inside one of the fuel line fittings, the larger of the 2

Just to be clear, what do you mean it's inside one of the fuel line fittings?  I removed both external fittings from the WUR (the larger one is the return) and they are just orifices-nothing inside.  Is the screen inside the WUR beneath where the fitting screws in?

On the M110 the WUR is under the intake manifold, only accessible from below.  Working under there is indeed like being in a rabbit hole...maybe worse.
Sorry if I wasn't clear.  Yes, it is as you describe it. 
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0