OM606 Fuel system - need some explaination please - PeachParts Mercedes-Benz Forum

MB300D81 · #1 04-02-2010, 07:11 AM

Hello diesel experts

I need some explaination for the fuel system on the OM606 E300 1997 TD.

Would someone please give names to these parts?

Does this engine have an electric fuel lift pump or is it mechanical like the ones in the W124 and W123?

This will help me a lot.

Thanks

muleears · #2 04-02-2010, 09:52 AM

Fuel line #74 goes from your MECHANICAL lift pump to the bottom of the shut off valve. Neither the pump nor the valve are numbered. The pump is the lower of the two.

#26 is your prefilter
#8 is the secondary filter
#'s 56,95,83,119,32 are your clear plastic fuel lines.

HTH

TMAllison · #3 04-02-2010, 01:30 PM

The fuel path travels in numerical order; 32, 56, 74, 83, and finally 95.

155 is the pre-heater/fuel thermostat.

The black plastic valve on the side of the IP is the Shut Off Valve.

Further back and lower on the IP is the metal lift pump.

GregMN · #4 04-02-2010, 04:46 PM

What issue(s) are you trying to deal with? This may help get the advice you need.

This fuel system does not really have a fuel shut off valve. I just reverses the flow of fuel to the IP to shut down.

If you are converting to VO you should fully understand the fuel flow to successfully alter it. Done properly, it will run great and not throw CEL's.

MB300D81 · #5 04-03-2010, 04:02 AM

You guys really rock.

Thanks so much for your help and replies.

What I am trying to do is replace the spin on fuel filter with a different brand "FleetGuard" that know to handle wvo better than the original mercedes filter and it is less expensive too.

Then I will install a heat exchanger to heat the fuel before the filter.

What I was confused about is that elecreic shut off valve.
I also was not able to see the lift pump. Seems to be hidden under the inlet manifold.

these are the issues I was trying to deal with.

Any thoughts and tips would be highly appreciated.

Thanks

red5jedi · #6 04-03-2010, 09:58 AM

If your looking at a two tank system, here is a good source.
http://jakesbenzconversion.blogspot.com/2008/04/fuel-plumbing-revisited.html

GregMN · #7 04-03-2010, 10:13 AM

Do a proper 2 tank fuel system that completely separates the 2 fuels.
Do not share filters.
Start up on pure diesel.
Switch to hot (160F min.) VO after fully up to temp.
On shut down, purge all VO out of the fuel lines in the engine bay with pure diesel.

Anything less and all the money you save on fuel costs (and likely much more) will be given back to the car in repairs.

If you are going to continue with your current path, please keep a log of your experiences and expenses to share with everyone.

The following threads my be helpful.

http://www.frybrid.com/forum/showthread.php?t=6097
http://www.frybrid.com/forum/showthread.php?t=9972&highlight=w210
http://www.frybrid.com/forum/showthread.php?t=13755&highlight=w210
http://www.frybrid.com/forum/showthread.php?t=7214&highlight=w210

mersas32 · #8 05-11-2010, 08:20 AM

hi,
i have the same car.
it is e300td.
i live in ireland, not many good mechanics thou.
the problem. can not start the car.
changed the o-rings, needed to bled the system 3 batteries died, on the fourth i got it runnig. The ''engine management light came on'' after 30 sec car cut -off.
could not start it. tryed everything. at last took the key out- locked the car- unlocked the car started straigth away.drove for a test drive.ok parkt then overnight- came next morning unlocked does not start.The fuel is not beeing sucked into the pump. took 1 pint of fuel put fed pipe into it .it does not suck. no air in a system!all fuel only.
towed it to mechanic. the same story. cant strat, no faults on the computer.!!
managed to start for 20 sec and then cuttoff again. I dont know what was he doing but now there is no click after 25sec in the pump after inition is on!!!there used to be a click just before the heating plugs click.
the shut of walve is ok and the computer sends the signal to it. I have to of these cars so easy to swap things to try.
so the pump seems to have 5 cables.

IS THERE a way to bypass or to give it 12v in to some of these cables to make it suck the fuel!!!????
what i mean is ii think imobiliser is blocking it somehow from sucking the fuel. so if i ''make'' it suck maybe it will be forced to start and suck it.
the mechanic is useless like everything else in this country!!!!he is mercedes offialy trained service!!!

any ideas.
the car is turning over and all good., just imagine it is not sucking the fuel to start!!!

KarTek · #9 05-11-2010, 09:17 AM

Hi Mersas32,

Did you happen to change the pre-filter? If so, there is an O-ring that is missing on the new filter and you have to buy it separately here in the US and I assume everywhere else.

Without the O-ring, it will not seal the system properly.

One other thing: Look VERY carefully at the above diagram in post #1. Make sure that you didn't accidentally swap the position of the lines #74 and #83 on the lift pump. The car will run with the lines swapped but it is very hard to start and may not start if there is less than 1/2 tank of fuel.

mersas32 · #10 05-11-2010, 01:04 PM

[QUOTE=KarTek;2464888]Hi Mersas32,
thanks for reply.
no i did not mixed them pipes up
and the seal is ok, the filter is ok.

TMAllison · #11 05-11-2010, 03:21 PM

Do yourself a favor and pull the pre-filter and "confirm" it has a oring installed under its rim.....the lift pump is mechanical and can't pull fuel up from the tank if there is a leak on the suction side of the pump.

mersas32 · #12 05-11-2010, 04:54 PM

Quote:

Originally Posted by TMAllison

Do yourself a favor and pull the pre-filter and "confirm" it has a oring installed under its rim.....the lift pump is mechanical and can't pull fuel up from the tank if there is a leak on the suction side of the pump.

yes
it is ok
the fuel is fed from a jar of diesel 20cm away from the pump.so basicaly it does not need to lift out of the tank.
so you would also skip the immobiliser version?

TMAllison · #13 05-12-2010, 10:32 PM

That is kind of important info to provide in the future. Always helps us to help you if we know the whole story from the git go.

If, when the key hits Pos #2 you do not hear the "click" of the SOV openning, it will never start. Or, if while running if it shuts off like the "key were turned off", without warning, in that event, if you are confident the SOV isn't leaking from underneath and its openning and shutting correctly wehn the key is cycles usually, your problem is probably the K40 relay that feeds its power. It usually causes intermittent electrical problems when it fails ( closes w/o warning, won't open and restart, etc). Got any other funny electrical issues??? Its the front most unit inside the computer box on the right side of the engine bay. Cracks appear in the PCB circut paths; requires magnification to see them.

mersas32 · #14 05-13-2010, 01:20 PM

Quote:

Originally Posted by TMAllison

That is kind of important info to provide in the future. Always helps us to help you if we know the whole story from the git go.

If, when the key hits Pos #2 you do not hear the "click" of the SOV openning, it will never start. Or, if while running if it shuts off like the "key were turned off", without warning, in that event, if you are confident the SOV isn't leaking from underneath and its openning and shutting correctly wehn the key is cycles usually, your problem is probably the K40 relay that feeds its power. It usually causes intermittent electrical problems when it fails ( closes w/o warning, won't open and restart, etc). Got any other funny electrical issues??? Its the front most unit inside the computer box on the right side of the engine bay. Cracks appear in the PCB circut paths; requires magnification to see them.

replaced that one aswell from my car.no difference.
It clicks straight after ignition is on, but after 30sec it does not click.it schould but just before the heater plug relay goes off.

TMAllison · #15 05-13-2010, 02:13 PM

No. The SOV clicks open at key pos 2 and stays open until the key is turned off. When closed the engine can't get fuel.

If you are hearing double clicks from the SOV either it, the K40 relay or the IFI/ECU are bad. It is remotely possible for the plug connecting the harness to the SOV to crack, loosen or otherwise fail to make a good connection and emmulate a shut down like an intermittent K40. I am the only one I've ever heard that happening to though. That plug is part of the overall engine harness. Is stocked in Germany.