Fuel rail pressure and pump concern
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
I meant that you first see if you see any leak without cranking, just to make sure the injectors are not leaking badly with even a low pressure (49psi as you said). You can also do this by unplugging the injectors and cranking -- that will give higher rail pressure and ensure the injectors are not actually leaking. Then you can crank and see the leakdown.
Theoretically the leak down test should be done when engine is running, so you have the normal rail pressure (~23000psi) and that will tell you how the injectors are working. For now what you need to make sure is just there's no injector leaking badly that's causing the rail pressure not building up.
Theoretically the leak down test should be done when engine is running, so you have the normal rail pressure (~23000psi) and that will tell you how the injectors are working. For now what you need to make sure is just there's no injector leaking badly that's causing the rail pressure not building up.
Senior Member
Joined: Apr 2012
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2012 ML350 Bluetec, 2015 GL350 Bluetec
OK if no fuel comes out then it can be concluded that the injectors are not leaking and the HPFP cannot build enough pressure in the rail. That can also be seen in the data from the fuel rail pressure sensor. Anything less than 100 bar is essentially 0. I think it's for sure that you need to rebuild your HPFP.
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Joined: Feb 2014
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W211 320CDI -04, W210 270CDI -01
There should always come some fuel out from inectors when cranking, but because of poor 40 bar rail pressure that is reduced for sure. But still if ijectors opens, always fuel comes out from tank line. Now its either fuel starvation on bad leak somewhere else. I just wonder why injector try inject (30-50mm^3) because injection permission should be given only after enough rail pressure (around 150-200 bar).
Senior Member
Joined: Apr 2012
Posts: 356
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2012 ML350 Bluetec, 2015 GL350 Bluetec
There should always come some fuel out from inectors when cranking, but because of poor 40 bar rail pressure that is reduced for sure. But still if ijectors opens, always fuel comes out from tank line. Now its either fuel starvation on bad leak somewhere else. I just wonder why injector try inject (30-50mm^3) because injection permission should be given only after enough rail pressure (around 150-200 bar).
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
OK if no fuel comes out then it can be concluded that the injectors are not leaking and the HPFP cannot build enough pressure in the rail. That can also be seen in the data from the fuel rail pressure sensor. Anything less than 100 bar is essentially 0. I think it's for sure that you need to rebuild your HPFP.
Last edited by vaseto; May 16, 2020 at 05:33 PM.
Senior Member
Joined: Apr 2012
Posts: 356
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2012 ML350 Bluetec, 2015 GL350 Bluetec
I don't think the ECU is built with such logic. The injection amount is calculated by lambda, load and intake air mass/pressure. The rail pressure will provide correction that lower than spec rail pressue will result in increase of fuel injection to compensate for the insufficient pressure, not reducing.
Member
Joined: Feb 2014
Posts: 242
Likes: 18
W211 320CDI -04, W210 270CDI -01
I don't think the ECU is built with such logic. The injection amount is calculated by lambda, load and intake air mass/pressure. The rail pressure will provide correction that lower than spec rail pressue will result in increase of fuel injection to compensate for the insufficient pressure, not reducing.
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Joined: Feb 2014
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W211 320CDI -04, W210 270CDI -01
I was always wondering that advice. Very true, pressure wave travels in rail and cause problems, even at full run. I have seen this happening in marine diesels. But during start, speed always varies a bit and pressure wave is highly depending on interference between pump piston timing and injection timing; resonance is happening only at certain frequencies = rotation speeds. And older HP pumps had only two possible 'timings' since slot ables only two 180 deg positions.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
OK I see the issue. The timing is required for earlier version of OM642 and the procedure is detailed in the WIS. However for later version of OM642 the timing is not required any more. At least on my 2012 and 2015 the WIS simply tells me to install the HP pump any way I want, while I put in a random 164.122 chasis in the search it gives me a detailed timing procedure when reinstalling the HP pump. If you need I can share the document.
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Joined: Apr 2012
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2012 ML350 Bluetec, 2015 GL350 Bluetec
It's just the same thing as if you have a small leak in a gasket and it requires a certain pressure to have any fluid (oil, water, etc) to actually leak out.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
OK I see the issue. The timing is required for earlier version of OM642 and the procedure is detailed in the WIS. However for later version of OM642 the timing is not required any more. At least on my 2012 and 2015 the WIS simply tells me to install the HP pump any way I want, while I put in a random 164.122 chasis in the search it gives me a detailed timing procedure when reinstalling the HP pump. If you need I can share the document.
Do you think I should buy WIS clone from China? Is it worth it? How would I know the specs for the HP? Let say I would like to rebuild it, I will get the O-rings kit, but what do I measure to check the specifics? I would like to salvage the HP if possible.
Last edited by vaseto; May 17, 2020 at 09:54 AM.
Senior Member
Joined: Apr 2012
Posts: 356
Likes: 66
2012 ML350 Bluetec, 2015 GL350 Bluetec
Not sure if mine does, but if you could share it would be great.
Do you think I should buy WIS clone from China? Is it worth it? How would I know the specs for the HP? Let say I would like to rebuild it, I will get the O-rings kit, but what do I measure to check the specifics? I would like to salvage the HP if possible.
Do you think I should buy WIS clone from China? Is it worth it? How would I know the specs for the HP? Let say I would like to rebuild it, I will get the O-rings kit, but what do I measure to check the specifics? I would like to salvage the HP if possible.
I got mine from a vendor on Ebay. It's only $10 so definitely worths it.
For the specs of the HP pump, Mercedes document wouldn't have it. You can take a look at the stamped info on the pump to get the manufacturer information, then look for rebuild kit for the specific model (the manufacturer model, not MB part number).
The pump and injectors are all different in early version vs later version of OM642. My 2012 and 2015 definitely don't need the "timing" procedure in this document. From EPC the injectors on my 2012 are 6420701187 while I put in a 164.122 chasis it gives me 6420701387 as the injectors part number. The HP pump on my 2012 is 6420701301 while the one on the 164.122 is 6420700301.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
This is the one I found for a 642.940 engine on a 164.122 chasis. If you give me your VIN I can verify if it's the same.
I got mine from a vendor on Ebay. It's only $10 so definitely worths it.
For the specs of the HP pump, Mercedes document wouldn't have it. You can take a look at the stamped info on the pump to get the manufacturer information, then look for rebuild kit for the specific model (the manufacturer model, not MB part number).
The pump and injectors are all different in early version vs later version of OM642. My 2012 and 2015 definitely don't need the "timing" procedure in this document. From EPC the injectors on my 2012 are 6420701187 while I put in a 164.122 chasis it gives me 6420701387 as the injectors part number. The HP pump on my 2012 is 6420701301 while the one on the 164.122 is 6420700301.
I got mine from a vendor on Ebay. It's only $10 so definitely worths it.
For the specs of the HP pump, Mercedes document wouldn't have it. You can take a look at the stamped info on the pump to get the manufacturer information, then look for rebuild kit for the specific model (the manufacturer model, not MB part number).
The pump and injectors are all different in early version vs later version of OM642. My 2012 and 2015 definitely don't need the "timing" procedure in this document. From EPC the injectors on my 2012 are 6420701187 while I put in a 164.122 chasis it gives me 6420701387 as the injectors part number. The HP pump on my 2012 is 6420701301 while the one on the 164.122 is 6420700301.
Senior Member
Joined: Apr 2012
Posts: 356
Likes: 66
2012 ML350 Bluetec, 2015 GL350 Bluetec
Here is the VIN WDD2120891A101459. So, you don't have the STAR clone, just a manual for mercedes? I was talking about this - https://bit.ly/2X3KczZ.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link.
https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
OK based on the VIN you should have 6420700501 or 6420701201 equipped. The EPC says 6420701201 is not for US or Japan version so I believe you have the 6420700501 but I'm not 100% sure. You might want to take a look at the stamped part number. The pump is older version so timing is required. I attached the document again but it should be the same as the one I attached last time.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link.
https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link.
https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
geniushanbiao, I already bought the manual from the link (thank you much for that). The HP pump is leaking from the bottom screw. I guess I will have to get that kit for it. So far good data for the pressure. See the pictures:
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
OK based on the VIN you should have 6420700501 or 6420701201 equipped. The EPC says 6420701201 is not for US or Japan version so I believe you have the 6420700501 but I'm not 100% sure. You might want to take a look at the stamped part number. The pump is older version so timing is required. I attached the document again but it should be the same as the one I attached last time.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link.
https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link.
https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
Senior Member
Joined: Apr 2012
Posts: 356
Likes: 66
2012 ML350 Bluetec, 2015 GL350 Bluetec
OMG!! This is so ****ing weird! Sorry for my language. I had a leak I just discovered under the car. At first I wasnt' able to see the origin. But then I noticed the top of the engine was wet - right under the batwing (can't notice it with the wing installed. So, I went ahead and re-tightened all HP fuel lines going to the injectors. First crank and the car started. No more leak either. My head just exploded. I Swear I followed the torx reqs for those. I have spent 3 weeks on this engine and finally there is the reason for low pressure. Dear Lord!! Now the car runs smooth, but I think its in limp modes. I know I have bad boost sensor on the EGR valve. But, look at the data from the scanner. It seems to me the exhaust pressure is low for that reason. Any ideas? Also IAT pressure?? Another weird code popped up - faulty DPF. Data showes very low ashes and soot - almost 0.
geniushanbiao, I already bought the manual from the link (thank you much for that). The HP pump is leaking from the bottom screw. I guess I will have to get that kit for it. So far good data for the pressure. See the pictures:
geniushanbiao, I already bought the manual from the link (thank you much for that). The HP pump is leaking from the bottom screw. I guess I will have to get that kit for it. So far good data for the pressure. See the pictures:
Not sure why the intake pressure is so low. Is your air filters clogged?
Last edited by geniushanbiao; May 18, 2020 at 06:12 PM.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
Did you make sure the mating surface is perfectly clean before connecting? The HP lines are very very sensitive to contamination and MB calls for any repair work with fuel line opening done under low dust condition.
Not sure why the intake pressure is so low. Is your air filters clogged?
Not sure why the intake pressure is so low. Is your air filters clogged?
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
They are showing, but I swapped the 2 sensors and the one showing the high value of 2500 is definitely bad. I did not change the AIr filters, only fuel filter. I never did an adaptation to air filter change and never had a problem.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
In addition, I had to replace:
1. Intake temperature sensor
2. Intake pressure sensor
3. Boost pressure sensor
4. Exhaust pressure sensor pending confirmation.
1. Intake temperature sensor
2. Intake pressure sensor
3. Boost pressure sensor
4. Exhaust pressure sensor pending confirmation.
