2010 w204 c220 cdi fuel pressure regulator

[Martyb-2007]

Good evening folks, just joined the forum thank you for having me! I’ve a 2010 c220 cdi w204 I need to change the fuel pressure regulator.. I’ve the part got but I can’t seem to find the high pressure pump it’s attached to? Can anyone help me? And is it hard to get at to change? Appreciate your help

 

[tpn]

I presume you are talking about the pressure regulating valve Y74. This screws into the rail. If it is the Y94 Quantity control valve-hopefully not- that goes directly onto the pump. Have a look here and determine what you need to change

https://tikobv.nl/m/CDI.pdf

ignore the Piezo injectors.

 

[Martyb-2007]

I presume you are talking about the pressure regulating valve Y74. This screws into the rail. If it is the Y94 Quantity control valve-hopefully not- that goes directly onto the pump. Have a look here and determine what you need to change

https://tikobv.nl/m/CDI.pdf

ignore the Piezo injectors.

Hi tpn,

Unfortunately not, it’s the QCV I’ve to change, pressure is too high, the car stalls intermittently when stopped at junctions etc so this is what it needs.. I’ve found the pump away down in below tonight there, I’m hoping maybe removing the filter housing will get me access to it? Any thoughts are greatly appreciated.. Many thanks

 

[supernoodle]

How did you determine it's the QCV that's causing the problem?

It's just that even if the QCV is fully open the PRV is capable of controlling pressure.

 

[tpn]

You need to be absolutely sure that it is Y94 that is causing the problem to avoid a lot of work. That pump is far down in the engine.
To take off the filter housing you have to take off the EGR cooler...and if you do not have the updated filter housing make sure you get a new one. The EGR will have to come off also, an annoying job.

I cannot remember if you can get to that valve without removing at least the throttle body and mixing unit (I should remember as I recently changed an inlet manifold but...)maybe from underneath, I cannot remember simply because I did not have to change one.

Having said that it is generally recognised that if the fuel pressure problem is on a cold engine it is the Y74 and if on a hot engine it is the Y94

This is a very interesting youtube video

 

[Martyb-2007]

See attached from another thread when I was researching.. I’ve already replaced the fuel pressure sensor on the rail and done a leak off test on the injectors which all appear to be fine.. this is the exact symptoms the car has.. so I picked up the Y94 from the stealers yesterday thinking it could be a handy enough change.. see also photo from my diagnostics

 

[tpn]

See attached from another thread when I was researching.. I’ve already replaced the fuel pressure sensor on the rail and done a leak off test on the injectors which all appear to be fine.. this is the exact symptoms the car has.. so I picked up the Y94 from the stealers yesterday thinking it could be a handy enough change.. see also photo from my diagnostics

Are you sure that that related to an om651 engine. I ask this as he suggests that it is an easy fix "AT THE FRONT" Without having a link to the whole thread it is difficult to figure out if he is relating to the front of the pump or the front of the engine.
It is certainly not an easy fix in an OM651 engine with the pump in situ, as in, getting there.

 

[alexanderfoti]

Agree with tpn

If the rail pressure control is poor when using the quantity control valve, then its the one on the pump. Its a lot of work on the 651 to get to it.

You must remove the EGR cooler, egr bracket, all of the vacuum system on top, throttle valve, intake pipework etc its a good 4-5 job all inc.

There is a test you can run where the computer will swap control methods and you can check which valve is giving the problems.

 

[Martyb-2007]

thanks guys.. I don’t mind the work in it, but I got a P0252 code that says the output of the QVC has a malfunction and the signal is faulty.. also P0088 that the fuel rail pressure is too high.. pretty much nailing the QVC. I tried to upload my screenshot of it but it’s too large.. what do you think? I really appreciate all your help.. I’m tackling it later this week, I had initially thought about dropping the engine down but I don’t think I could drop it far enough..

 

[alexanderfoti]

On first start, rail pressure is usually managed by the quality control valve (regulator on rail). After 30/60 seconds it switches to quantity control valve.

If your rail pressure is smooth at cold start until the control strategy changes, its a good indicator.

 

[Martyb-2007]

On first start, rail pressure is usually managed by the quality control valve (regulator on rail). After 30/60 seconds it switches to quantity control valve.

If your rail pressure is smooth at cold start until the control strategy changes, its a good indicator.

Totally smooth at the start, nearly like an automatic choke, all is good.. starts to play up when it warms up. I think I’m on the right path, let’s hope so lol I will keep you all posted how I get on..Shocking the stripping to do to get at it, I’d imagine once I reach it I’ll have it changed pretty quickly.. not much room around it for a 2.2 engine, I can only imagine what a c63 or even a 350 would be like

 

[alexanderfoti]

C63 is quite good.

This is one of the more pita jobs on this engine but its just time consuming rather than hard!

 

[tpn]

Totally smooth at the start, nearly like an automatic choke, all is good.. starts to play up when it warms up. I think I’m on the right path, let’s hope so lol I will keep you all posted how I get on..Shocking the stripping to do to get at it, I’d imagine once I reach it I’ll have it changed pretty quickly.. not much room around it for a 2.2 engine, I can only imagine what a c63 or even a 350 would be like

If you run that youtube video you will see where they also state that \y74=cold engine; Y94=hot engine.
A lot of stripping...and because of that do clean the EGR and throttle body etc and use new Mercedes seals.
If you do not have the upgraded fuel filter housing replace it, as there are only two types of the old housing; those that have failed or those that are about to fail. They are relatively cheap from Mercedes