Fuel injection pump starvation with a good lift pump - PeachParts Mercedes-Benz Forum

whunter · #1 03-09-2009, 11:44 AM

Fuel injection pump starvation with good a good lift pump is becoming more common as the bypass valve spring gets weaker with age.
A weak bypass spring allows too much lift pump pressure to flow back to the fuel tank = starving the injection pump for proper fuel volume.

The solution is to install a new (or good used) bypass valve for your engine application.

MB# 0000747284
Diesel fuel return valve/banjo bolt, back of injection pump by engine block, at nylon return line going to fuel filter housing.
At this moment (March-12-2009), I have verified five new units remaining in north America.

Application list:

OM615. 910, 911, 912, 913, 914, 915, 916, 917, 919, 930, 932, 936, 937, 938, 939, 940, 941, 942, 943, 944, 963, 970

OM616. 911, 912, 913, 914, 915, 916, 917, 930, 932 933, 934, 936, 937, 938, 939, 940, 960, 961, 963

OM617. 910, 912, 931, 932, 933, 950, 951, 952

OM621. 912, 913, 915, 916, 918, 919, 930, 931, 932

NOTE:
You should replace the banjo bolt/valve seal rings at this time.

Two of the following
Item Number: 007603012111
Main Category: MERCEDES BENZ
Description: SEAL RING, BANJO WASHER
Weight: 0.02

Diesel fuel return valve/banjo bolt, back of injection pump by engine block, at nylon return line going to fuel filter housing.

MB# 6010700146
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_Search.cgi?SUPERCAT_FLAG=Y&make=MBZ&please_wait=N&forumid=&threadid=&description_side=007603012111&GoSearchSideFlag=&command=DWsearch&command=DWsearch&REFINE=Y&FORUM_REFER=&SUPERCAT_FLAG=Y&make=MBZ&description=6010700146&x=47&y=10

Application list:

OM601. 911, 912, 921, 940, 941

OM602. 911, 912, 930, 931, 938, 939, 940, 941, 942, 946, 947, 948, 961, 962, 990, 991, 993

OM603. 912, 913, 931, 960, 961, 962, 963, 970, 971, 972

OM616.963

OM661.911

OM662.911

NOTE:
You should replace the banjo bolt/valve seal rings at this time.

Two of the following
Seal ring
MB# 007603012405
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_Search.cgi?SUPERCAT_FLAG=Y&make=MBZ&please_wait=N&forumid=&threadid=&description_side=6010700146&GoSearchSideFlag=&command=DWsearch&command=DWsearch&REFINE=Y&FORUM_REFER=&SUPERCAT_FLAG=Y&make=MBZ&description=007603012405&x=23&y=9

Diesel fuel return valve/banjo bolt, back of injection pump by engine block, at nylon return line going to fuel filter housing.

MB# 6010700646
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_Search.cgi?SUPERCAT_FLAG=Y&make=MBZ&please_wait=N&forumid=&threadid=&description_side=007603012405&GoSearchSideFlag=&command=DWsearch&command=DWsearch&REFINE=Y&FORUM_REFER=&SUPERCAT_FLAG=Y&make=MBZ&description=6010700646&x=33&y=4

Application list:

OM601. 913, 942, 943, 970

OM605. 910, 911, 912, 960, 962

OM606. 910, 912, 961, 962, 964

NOTE:
You should replace the banjo bolt/valve seal rings at this time.
Two options, VIN# needed to determine the correct ones.

Seal ring
MB# 0179972248
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_Search.cgi?SUPERCAT_FLAG=Y&make=MBZ&please_wait=N&forumid=&threadid=&description_side=6010700646&GoSearchSideFlag=&command=DWsearch&command=DWsearch&REFINE=Y&FORUM_REFER=&SUPERCAT_FLAG=Y&make=MBZ&description=0179972248&x=41&y=6

or

Two of the following
Seal ring
MB# 007603012102
http://www.pelicanparts.com/cgi-bin/ksearch/PEL_Search.cgi?SUPERCAT_FLAG=Y&make=MBZ&please_wait=N&forumid=&threadid=&description_side=0179972248&GoSearchSideFlag=&command=DWsearch&command=DWsearch&REFINE=Y&FORUM_REFER=&SUPERCAT_FLAG=Y&make=MBZ&description=007603012102&x=25&y=12

NOTE – All prices on special order parts subject to change without notice.

diametricalbenz · #2 03-09-2009, 12:10 PM

Where exactly is the bypass valve and how is it accessed for repair?

#3 03-09-2009, 12:27 PM

No need to spend $30 replacing the valve, the proper solution is to stretch out the spring to 27mm per FSM.

Fuel pressure relief valve adjustment

Alastair · #4 03-09-2009, 01:01 PM

Quote:

Originally Posted by ForcedInduction

No need to spend $30 replacing the valve, the proper solution is to stretch out the spring to 27mm per FSM.

Fuel pressure relief valve adjustment

Unfortunately, Not ALL valves are dismantleable to gain access to the spring.....!

Diesel911 · #5 03-09-2009, 01:34 PM

I have watched the thread on the spring stretching and wondered; has any one tried shimming the spring?
Since the spring is does not have a heavy pressure even aluminum from a Soda can could be used to make the shims; or possibley gasket material. Stretching the spring is a 1 way proposition. With shims you can adjust the pressure you want.

whunter · #6 03-09-2009, 01:35 PM

Quote:

Originally Posted by ForcedInduction

No need to spend $30 replacing the valve, the proper solution is to stretch out the spring to 27mm per FSM.

Fuel pressure relief valve adjustment

There are two designs of this valve, (pictures attached).
The servicable type, and the press sealed type.

* The servicable type may be adjusted, until the spring breaks,
(I have found several with broken/damaged springs inside).

* The press sealed type must be replaced.

whunter · #7 03-09-2009, 01:48 PM

Quote:

Originally Posted by Diesel911

I have watched the thread on the spring stretching and wondered; has any one tried shimming the spring?
Since the spring is does not have a heavy pressure even aluminum from a Soda can could be used to make the shims; or possible gasket material. Stretching the spring is a 1 way proposition. With shims you can adjust the pressure you want.

I have been forced to do this several times with damaged springs.
Fabricating a safe pressure test unit took a couple of hours, shimming took another hour, the repair survived six months, (damaged spring failed).

The damaged valve was replaced, part cost + 0.5 hour labor.

It cost the owners far less to replace than repair in a professional shop.

compress ignite · #8 03-09-2009, 02:02 PM

the dumbfounding question.

Your Hunterness,

Is there not a New Spring available from Mercedes?
(which would already have the proper length and Brinell)
(If so ,Part Number, sil vous plait)

Thank you so very much!

whunter · #9 03-09-2009, 02:20 PM

Quote:

Originally Posted by compress ignite

the dumbfounding question.

Your Hunterness,

Is there not a New Spring available from Mercedes?
(which would already have the proper length and Brinell)
(If so ,Part Number, sil vous plait)

Thank you so very much!

I have checked with MB many times through the years looking for springs, MBUSA state they where never available, and sends you to the dealers for a new valve.
The engineers I have talked with confirm the spring data is proprietary, patent/copyright.

Diesel911 · #10 03-09-2009, 11:35 PM

Quote:

Originally Posted by whunter

I have been forced to do this several times with damaged springs.
Fabricating a safe pressure test unit took a couple of hours, shimming took another hour, the repair survived six months, (damaged spring failed).

The damaged valve was replaced, part cost + 0.5 hour labor.

It cost the owners far less to replace than repair in a professional shop.

Some one willing to stretch a spring to achieve an unknow pressure might not care about the above.
They just want to see what is going to happen if they stretch the spring.

Diesel911 · #11 03-10-2009, 01:39 PM

Quote:

Originally Posted by compress ignite

the dumbfounding question.

Your Hunterness,

Is there not a New Spring available from Mercedes?
(which would already have the proper length and Brinell)
(If so ,Part Number, sil vous plait)

Thank you so very much!

Maybe someone will buy one of the new Over Flow Valves and take the spring out so they can find a source of the springs.

C Holmes · #12 03-10-2009, 05:15 PM

I have a M603 in an 87 300TDT and lately it will start right up and then stall and is very hard to start after that.
Once going it is fine.
Does this engine have a fuel pump other than the inj pump?
Is there a check valve in the line that could have failed?
Anyone have any idea what could cause this?
I have just changed the filters and it hasn't done it since but it only does it once in awhile anyways.

Diesel911 · #13 03-10-2009, 06:27 PM

Quote:

Originally Posted by C Holmes

I have a M603 in an 87 300TDT and lately it will start right up and then stall and is very hard to start after that.
Once going it is fine.
Does this engine have a fuel pump other than the inj pump?
Is there a check valve in the line that could have failed?
Anyone have any idea what could cause this?
I have just changed the filters and it hasn't done it since but it only does it once in awhile anyways.

If it is doing this only after it sits someplace for a long time it could be that it is "losing it's prime"; meaning that some of the Fuel that has filled the hoses up to the supply pump is leaking back to the tank when it sits a long time ( because of your Check Valve question I think you have though of this already).
When I have seen this on other vehicles the cause most often is tiny air leak/s in the Fuel Hose connections or cracked Fuel Hoses. However, I do not know enough about the newer MBs to guess what else it could be.

If your Fuel Supply Pump has a Hand Primer on it; it would be easy to determine if the above is the problem. Because, you could pump the Hand Primer and if it starts OK everytime you use the Hand Primer that would give an excelent clue that you were losing the prime.

C Holmes · #14 03-10-2009, 06:32 PM

Well it seems this is so but it will do it after only sitting for a short while. Is there an auxillary fuel pump? Also where is the hand pump? I know there must be one but I can't seem to locate it.