i have 2010 R350. 170k miles, was hard starting and stumbling when warm. In trying to keep this slightly condensed, i have a replaced the low pressure tank pump for good measure. It made no difference. I have a gl320 cdi that shares several fuel parts, so I have tried swapping different parts including HP fuel pump and nothing made a difference. Still had hard starting, several cranking attempts that would time out and eventually it would start. So, finally, I have worked my way to the injectors. Yesterday, I did a leak test of the injectors and the front two Injectors on the driver and passenger side were clearly clogged or had a problem and filled the fuel collection container in 1 min.. Which brings me to today's plea for advise, I pulled both injectors, one at a time, so not to make mistake of putting an injector in wrong spot. I cleaned each by laying tip/nozzle in a sonic cleaner bath of seafoam injector cleaner, that appeared to be very effective. Then moved to the bench and removed the nozzle/tip and cleaned the nozzle components individually, and reassembled. I am 100% confident in reassembly and a test of the jets in the tip end with spray brake cleaner produced very good dispersion spray. I didn't disassemble more than the nozzle components. During removal in HP fuel lines to passenger side, I had to unscrew all three injector steel lines from the common rail, lossen the rail, and gently leverage it slightly to remove the front injectors steel line. I reassembled everything. And tried to start but now it won't start, even after many cycles of the cranking cycle. I use an inexpensive OBDII Bluetooth code reader that monitors fuel rail pressure. Before injector removal process I had 75psi on low pressure when turning key to activate LP pump, then the HP psi would engage on turn of key to the start position, with 1700+ psi and eventually start after several cranking cycles. Now upon reassembly, my 75psi LP is there, but the HP is only hitting 300, give or take but not the 1700+ psi needed to start. Now, I can't get it to start, just cranking cycles. I have no leaks on the low pressure return lines or at any of the common rail steel connections. I have no idea how the clean injectors, no leaking LP or HP lines would cause loss of HP rail pressure. I would think any leak on HP side would be obvise, but nothing. I did take off one LP return connector to ensure the injector was getting fuel. Any advise? I will be spending all day tomorrow removing the fuel rail to make sure all fuel and electrical connections are good. I don't get the HP loss. The HP pump is powered by the engine gear turning, not eclectically so how could I loose HP pressure, I didn't disconnect any rail sensors just the injectors, map and maf sensors. On a side note, the cylinders of the clogged injectors appeared to have good amount of Black sludge on the tips on the injectors, when I first pulled them and after the cleaning. Any idea on how to clean the combustion chamber the help clear any crap in the cylinder. Acetone, maybe?

Have you bled air from the HP fuel pump.? **** can get expensive quickly if not.

No, I thought cleared as the LP pump primed the system. How do you bleed th HP pump. When I swapped with gl320 I had no problems. I can hear the bleeding when engaging th LP when turning key to position before start.

You hear the LP side feeding diesel to HP pump..just a thought. My HP pump has a bleed procedure, yours likely does toonas almost every one I have seen does somehow

I can't find any procedure. Do you have any idea how to do it, even for a different may be of help.

Ok, try injector bleed test again and see what happens? See if you get air bubbles. I've always cracked lines open on mechanical injection but this is not recommended for the HP pump apparently though I have done it. You may have other Issues? Did you recently swap LO filter under hood, it has an air bleed in middle top, good idea to use prior to firing up.

Yes I replaced it but that was first thing I did when started having problem of starting. Vehicle been running for months since, this loss of pressure is only after I removed the 2 injectors, cleaned then and replaced, I have cracked open the steel fuel feed lines to let bleed, fuel is there, but OBD indicates 75psi LP prime the 2-300psi HP with no fire just crank. Don’t want to get lost on basic stuff like fuel filter, I’ve already been there this is what I would say is slightly more advanced than checking fuel filter pressure.

You may have an injector leaking on delivery side causing pressure bleed, bad FPR/FCV in CP3, pinched fuel LP delivery line....bad sensor? It's time to go serious on this one

Yes I replaced it but that was first thing I did when started having problem of starting. Vehicle been running for months since, this loss of pressure is only after I removed the 2 injectors, cleaned then and replaced, I have cracked open the steel fuel feed lines to let bleed, fuel is there, but OBD indicates 75psi LP prime the 2-300psi HP with no fire just crank. Don’t want to get lost on basic stuff like fuel filter, I’ve already been there this is what I would say is slightly more advanced than checking fuel filter pressure.

As a diagnostic technician, one of my day jobs, that is always my first question to tech support customers via phone or in person or email. “What did YOU touch last”? I’m not slamming you, obviously your car had an issue or you would not have worked on it and honestly I find people who DIY on modern cars inspiring. I’d say that question alone leads to 80+% of actual problems. The injectors MUST be leak tested at firing end, if in the ultrasonic tank something were loosened up which is preventing the injectors Pinole from closing fully, well it an answer. Anyone have a spare couple of even bad injectors near you? Might be insightful if not a solution.

Been working on it all day. Here's the run down. The HP is good and operating, I have good pressure from filter to HP. Pulled the line at he HP side and filled 16oz water bottle in about 2 seconds. But before that, I took my functioning HP on my gl 320 and switched them. The gl is same with 3k psi at start with the R350 pump and the R is still at 75-95psi LP and 260-340 at cranking (no start of course). I changed passenger side fuel common rail and confirmed all steel line connections, while I was at it I pulled the other 2 injectors and did the same cleaning of the tip/nozzle, all were filthy but not so bad as several photos on site of Black Death. So that makes all 3 injectors on passenger side pulled, cleaned, great spray dispersion, reinstalled with white ceramic paste, new LP o-rings and no leaks on LP side. Driver Side has 2 cleaned injectors, same common rail, all steel connections are not leaking.

The injector cleaning was undertaken after everything else from tank fuel pump to fuel rail was was checked or replaced, including engine coolant sensor, cam and crank sensors and I did an injector leak test that both #1 of passenger and driver side failed and # 3 on driver side filled bottled halfway. Surprisingly, #2(middle) passenger side had no leak yet when pulled, it had beginning of black in injector tube and was fairy dirty at nozzle.

So here I sit after a 6-8 hours under the hood trying to figure this puzzle. Again it was hard starting, but would start after the second to fifth cranking cycle and now it won't start and I can't do another leak test without it starting.

background of my ownership is only for past 15k miles and I don't know the previous history. According to car fax it was 1 owner for 90k sold to Mercedes dealer salesman and then his dealership sent it to auction after his 50k miles, where I found it.

i did waste $180 at the dealer to have a diagnosis, only to have the characters say it needed all six injectors and it would work for $4000. Nothing else was wrong with it, no DTC codes and it was running, sort of.

Im not a shop mechanic but this is my 3rd om642, and my indie has let me assist a lot on repairing them, no injectors though.

the injector series # do match the ecu, so unless I somehow mixed the front 2( #1 on passenger and driver) but yesterday I thought of that and swapped them and still no fire and no HP (3k psi).

I think that covers it. Except to say the dealer is out of the question, the cars not wort putting that much $ into it. I'll part it out with my Indy before the damn dealer ever gets my money. I only use their parts dept. what a difference in staff departments under one roof.

While typing your response came in, so let me add. The only part of the injectors I touched were the nozzles, I didn't submerge the body above the nozzle cap especially the connector end , and very careful to use sterile environment to disassemble and reassembly. I can see why the ones that failed the leak test, the tips were covered in crud.

Another note on the injector nozzles, the nozzle only has 4 inernal parts, the tip with its six jet holes, the needle or shaft and a short spring with the bushings and each end and they slide onto the needle shaft. I know your laughing at the terminology but I'm to frustrated to find the correct name of those 4 components. I figure you guys helping with very much appreciated observations, are good enough to know what I'm talking about. So please forgive my shorthand.

https://cimg8.ibsrv.net/gimg/www.mbw...6e6a3a5e3.jpeg
https://cimg9.ibsrv.net/gimg/www.mbw...eff20dfcc.jpeg
https://cimg0.ibsrv.net/gimg/www.mbw...53a856a6e.jpeg
https://cimg5.ibsrv.net/gimg/www.mbw...3bc147054a.png
So I’m a little more than just s diagnostic tech. In my industry I’m sort of the place of last resort for both customers and OEM’s to fix odscure problems or to failure analyze motors. I did one multi week mind **** job for KTM back in the 950cc twin cylinder days where a new motor had only 60 psi compression on one cylinder and 190 on the other. The bike was brought by KTM for impossible to carburete correctly issues..(had been to all five Texas KTM dealers) .weeks later I’d find an inlet camshaft sprocket pressed on at the wrong index closing at about 140 degrees ABDCC lol. Their payment was in full and the generous. Root cause failures are the fun ones. The call me the “the last Jedi” or “Great master” or “Yoda” which I enjoy, but it makes me feel older than my 44 years suggest. This last week I’ve been trying to prove a bike reliable with zero loss of functionality after removing a malfunctioning “tip over” switch...burned a whole tank of fuel though it on dyno, RBW bikes with cruise control are freaking brilliant on dyno...set brake for highway speed/rpm....bring up to say 17-25 bhp loading depending on aero, adjust cooling fans as needed...turn off lights and break out DSLR and tripod because if you don’t the next 1/2 hour is gonna be pretty boring and miserable in a 100F test cell lol. Drink LOTS of water, like a liter every 30 minutes above 100F.

How this relates to your issue: I suspect you have two or more bad injectors. I personally own a mechanical injection cleaning rig rated to about 10 Bar and an EFI (gasoline/ethanol/methanol/propane) cleaning rig that also flow tests and balances, spray patterns and leakage testing on up to six cylinders at a time. They may be out there but I know NOBODY with a similar setup for Common rail injectors that can test from 30 to say 2000 Bar pressure. I know nobody yet I can trust to clean common rail injectors. These are different beasts. Little 48 psi Marelli or Bosch gasoline sprayinjectors they are not. Maybe someone here knows of an American shop that can fully test and clean these specialized injectors, please let us know if this resource is out there. I also know nobody I trust here in the USA to modify or upgrade our injectors to a greater flow volume or different spray pattern. This doesn’t mean there isn’t anyone, just not anyone I have heard of from multiple sources as an awesome shop.

The parts you you refer to are what I call the firing end nozzle parts set. I tried to clean these areas on my Ford 6.0 before sucking it up and paying darn near $5600 USD at dealer for “new” injectors from Ford which as it turns out are all remains now...and 1 went bad 35 miles into 750 mile round trip towing a cargo trailer. . My attempts made ZERO difference. It is possible your Injection Pressure Regulator has failed or the Flow Control Valve or the Rail Pressure Sensor though I doubt that part as it’s readings seem accurate when your vehicle is running.

How much diagnostic computer power power do you have, at least equivalent to Star or full version of iCarSoft MBII? I wish this were easier to explain and these parts more common.

https://cimg2.ibsrv.net/gimg/www.mbw...7adc63f521.jpg

These were clean and I only removed them for photo but all components easily fit together with no sophisticated springs or tools needed.
https://cimg3.ibsrv.net/gimg/www.mbw...635fa05cf9.jpg

Originally this is all the parts I touched
https://cimg3.ibsrv.net/gimg/www.mbw...9687f168ac.jpg
https://cimg1.ibsrv.net/gimg/www.mbw...ef519ef43b.jpg
https://cimg7.ibsrv.net/gimg/www.mbw...81b963ec1a.jpg
Well, I only have a OBD II bluetooth and free on-line app. So I know I should give you a moment to stop laughing, but the dealer STAR said all was well with no code, matching #s good even compression, no psi out of range, absolutely nothing but "replace all 6 injectors and that will fix it", I went after to my Indy, he's has a STAR and stood with him as we verified all as well, nothing could be determined by STAR....twice, even though the problem or its symptoms were obvious, now my Indy thinks it's fuel system related but I haven't been back to him yet to solve this, I thought I would give it a shot first starting with the leak test and identifying the 2 injectors, then I though why not try it DIY since at worst it will go to him to replace the injectors or some other fuel/starting repair. Only thing I didn't count on is it not starting now, so a tow may be coming but that's what AAA for.

Peter, took your advice, took a break this am, played 18 holes. Following several of your suggestions, go back to where I last had something right and go from there. So, pulled both left and right #1 injectors and check assembly, I took photos of the injectors parts and very very carefully reassembled. Micha, the have the black return nip's. I hope I can get the photos loaded. I definitely have fuel, but again I have no start, LP psi is 75-95 and cranking HP to 300-350 psi. Next step is to switch driver side common rail with regulator and switch the two #1 injectors in case I mixed them.

I case it confused anyone, I had a spare set of common rails with regulator and sensor, the were the originals that replaced with my spares, that neither made a lick of difference in trying to fix the original problem, so I'm only going back to the originals.

so I flipped the front 2 injectors and it made no difference, 75psi Los side, 266psi on crank, no leaks, haven't D.C. hand rail yet, need to vent with a cold beverage. GD,GD,GD,GD, THIS IS FRUSTRATING!

any suggestions on using some type of starting fluid to at least get it to fire. I have never done it eon a diesel. BTW, the glow pugs are all good, I checked with meter days ago and all are good.

Right, I understand, well stated about having rebuild. When I did the test, obviously the vehicle could start and run. The tips were severely clogged which I though was potentially the cause of the Back-up or leak. I'm surprised the nozzle cleaning would cause a complete failure, I thought a worst it would stay the same (running but hard starting). Tomorrow is search for rebuild shop. Thanks for help to all.

Give me the exact failure order...ran rough but started...and then....fill in the blanks....I’ll try...

First, on 6 hr highway run at 80+ mph vehicle stalled and wouldn't start, tow truck dropped it at house and it started, since it was hard starting, repeated cranking attempts but would start after 2 to 7 attempts, ran well when started but some infrequent stumbling on excelleration and never another stall. I started with basics of fuel filter, tank pump, bad fuel, and some sensors. Nothing changed hard starting, including HP/injector pump swap with the GL. Nothing changed. Used spare common rails, nothing changed, used several LiquiMoly injector cleaner, nothing helped, had my 1st Indy surrender and said to pay the deal extortionists for complete STAR diagnosis, worthless! all parameters good but recommended all 6 new injectors. Old Indy retired 70 year old, and new one is Mercedes specialist as well but does have a STAR. He thought dealer was crazy as well and hooked up his STAR and all good from injectors to cylinder compression, all good. Wife out of town for week and I had a chance to to do leak test, 2 failed, but the vehicle would start and run. Pulled the 2, cleaned the nozzles and replaced, now vehicle will not start, just crank, and the highest fuel pressure recorded is 300psi during cranking. So even with failing 2 injectors IT STILL Started. I don't fully understand how cleaning the 2 nozzles caused further degradation to not starting. I feel if I could just get it to fire once it would clear all the fuel and crap out even if it only fired the combustible solution and failed to continuously run, at least I would know it is capable of combustion, and I can focus on injector and fuel delivery.

this is a fairly new to me vehicle that had 140k miles on it, so the parts I replaced, seemed good idea even if they weren't the problem. Just to have a good staring point for next 200k. I have 300k on my gl320, so again I understand this platform and I do nearly all my own repairs unless it requires a lift or the labor cost is better than my time.

Does tach move when cranking? If not maybe cam or crank position sensor didn’t get plugged back in or into wrong thing if possible?

Already checked those. The tach doesn’t move.