C220 CDI fuel pump problems

[JonathanLingham]

A slight weep from the top lobe of my W203's high pressure fuel pump, so I whipped it out and replaced it with a reconditioned unit from Bosch. This all went swimmingly well...but the car won't start. Any thoughts as to why not? I can't see air in any of the pipes. I've drained the battery trying to start it.

 

[mersum1es]

Low pressure hoses in wrong order is most common reason, but on other forum you stated how they are (front pump connection to rail). You may open aux pump delivery connection when someone cranks engine, if fuel starts pouring put it back fast, you are getting fuel from tank. Injector leak may prevent pressure to rise, check that all injector plugs are tight.

Do you have shut down valve? Check wirings there. Check that shut down valve (engine side) hole check valve is working, it should go inside by moderate push:
http://www.mese.fi/forum/userpix/12179_pumppu1_1.jpg

Edit: Sure you have at least 1/2 fuel? Old pump may have caused 'saddle tank' syndrome...

 

[JonathanLingham]

Low pressure hoses in wrong order is most common reason, but on other forum you stated how they are (front pump connection to rail). You may open aux pump delivery connection when someone cranks engine, if fuel starts pouring put it back fast, you are getting fuel from tank. Injector leak may prevent pressure to rise, check that all injector plugs are tight.

Do you have shut down valve? Check wirings there. Check that shut down valve (engine side) hole check valve is working, it should go inside by moderate push:
http://www.mese.fi/forum/userpix/12179_pumppu1_1.jpg

Edit: Sure you have at least 1/2 fuel? Old pump may have caused 'saddle tank' syndrome...

Low pressure hoses in wrong order is most common reason, but on other forum you stated how they are (front pump connection to rail). You may open aux pump delivery connection when someone cranks engine, if fuel starts pouring put it back fast, you are getting fuel from tank. Injector leak may prevent pressure to rise, check that all injector plugs are tight.

Edit: Sure you have at least 1/2 fuel? Old pump may have caused 'saddle tank' syndrome...

Thanks for getting back to me. Before I swapped the pump, the car started and ran fine. It has 3/4 tank of fuel. My thinking is that there's either air in the system which needs purging, and my battery won't turn the engine for long enough before running flat (1 minute). Or I've got those hoses the wrong way round (but I've had them in both ways and it won't fire).

I'm assuming the hose at the back of the photo is the fuel feed coming in from the filter/tank (my car doesn't have that part on the far left of the diagram, above the number 137. Is that the shut off valve? My hose goes straight into the pump). And the one at the front is the return from the common rail? Do you know if this is right?

Another possibility...the white sponge "O" rings on the connectors have seen better days. Is their condition crucial...I've seen various posts offering different opinions.

 

[mersum1es]

yep above 137 is shut valve, it was discontinued somewhere mid of 2001... yes aux pump delivery goes engine side (back of photo) hose between numbers 137.

You need to figure out are you having fuel from aux pump to hp pump. Disconnect hose like I said, fuel will come out but not with force. If no you have problem lifting fuel from tank. If yes then its tricky without diagnostic tool, low rail pressure means you have a leak somewhere or faulty hp pump, electrical culprit can be open injector circuit or either angle sensors (cam/crank).

Edit: was white sponge really under the connector, I recalled is would have been under flange which push connectors on their places... well I may remember wrong,,, but it should have not big effect if you won't see air bubbles and delivery line from aux pump is not leaking out.

 

[JonathanLingham]

yep above 137 is shut valve, it was discontinued somewhere mid of 2001... yes aux pump delivery goes engine side (back of photo) hose between numbers 137.

You need to figure out are you having fuel from aux pump to hp pump. Disconnect hose like I said, fuel will come out but not with force. If no you have problem lifting fuel from tank. If yes then its tricky without diagnostic tool, low rail pressure means you have a leak somewhere or faulty hp pump, electrical culprit can be open injector circuit or either angle sensors (cam/crank).

Edit: was white sponge really under the connector, I recalled is would have been under flange which push connectors on their places... well I may remember wrong,,, but it should have not big effect if you won't see air bubbles and delivery line from aux pump is not leaking out.

Thanks, this is helpful. I've popped outside to confirm that the hoses are correctly connected. They are.

I tried starting it, but no dice, and the battery ran completely flat after two attempts. For the second attempt, I tried autostart, and then ran round to the front of the engine while it was still cranking. When it stopped, a couple of large bubbles rose slowly up the clear vertical pipe to the (?) fuel shut off above the pump. I need to work out whether this is old air that got in when I changed the pump, or new air being drawn in. And if so, where the leak is (I can't see any fuel leaking out anywhere).

Overnight I'll fully charge the battery and try to auto-purge the battery by holding the ignition key. Some posts say it might take a full minute....or more...for the system to clear. If it won't start, I'll test for fuel delivery as you suggest. And prod the valve just inside the pump to make sure it's opening properly.

Thanks again for responding. If you have any lightbulb moments overnight, please share them with me.

Cheers.

Jonathan

 

[mersum1es]

Old pump was starting ok? If you have energy, try old pump once more... to rule out faulty hp pump.

I remember couple of cases where measuring connection 135 was leaking. But like said there may be fuel because fuel is not moving through rail pressure control valve (pressure not rising).

In case of trouble getting fuel from tank, do you have separate paper fuel filter? In that case you can fill up filter bowl to fasten fuel feed. With metal filter you may try feed the aux pump directly from fuel canister.

Injector leak can be also measured without engine running, 1 minute cranking not necessarily continuously.

And Yes long crank may help, I was one time diagnosing car with bubbles in filter line AND leaky injector. There car was starting if key was hold crank position pretty long time (it felt taking ages...) but car owner knew it will eventually start

I always use SDS so I know is it fuel problem or not.

 

[JonathanLingham]

Old pump has been returned to the dealer...the new one was bought on an exchange basis. I had toyed with doing my own reconditioning...I see repair kits (new seals, gaskets, etc) are available for about €20. Probably best I didn't, given the current circumstances! The exchange unit cost me about €200 all in.

No reason to believe the injectors are leaking (which would reduce compression pressure). I've had a couple of injectors go in the past, know the symptoms (smell, chuff-chuff sound), and check them regularly.

Is it worth trying to 'catch the bubbles' rising in the vertical pipe at the front, and top up with fuel there? Or shall I just go for the long crank?

Really appreciate your continuing advice on all this. I'll let you know how I get on.

 

[mersum1es]

I am talking 'leak back test', injector leaks to tank always slightly when it operates (pilot stage flow). But when inner seals of injector wears too much, tank leak increases until pump cannot produce enough pressure when engine rotates only at cranking speed. This is often temperature sensitive too. I am not worried couple of floating bubbles when car is not running, but fuel should be get flowing.

 

[JonathanLingham]

Low pressure hoses in wrong order is most common reason, but on other forum you stated how they are (front pump connection to rail). You may open aux pump delivery connection when someone cranks engine, if fuel starts pouring put it back fast, you are getting fuel from tank. Injector leak may prevent pressure to rise, check that all injector plugs are tight.

Do you have shut down valve? Check wirings there. Check that shut down valve (engine side) hole check valve is working, it should go inside by moderate push:
http://www.mese.fi/forum/userpix/12179_pumppu1_1.jpg

Edit: Sure you have at least 1/2 fuel? Old pump may have caused 'saddle tank' syndrome...

Thanks for your earlier advice. My car’s still not starting, after various efforts to fix it (luckily I have another car). My car is made after the separate shutdown valve was discontinued. This afternoon I removed the two plastic fuel lines entering the HP pump, to see if the shut down in the pump was operating properly. It’s very fiddly in there, and because of poor light I couldn’t quite see what was in there. But it didn’t look as though a valve was fitted...I couldn’t see the end of the circlip visible so clearly in the photo (below) you posted a few years ago. Is it possible I’ve been sent the wrong HP pump?

 

[mersum1es]

I'm not 100% sure but if you don't have shut down valve, there may not be check valve at all (my OM612 has both, only pump I have opened myself).

Have you made leak back test, is aux pump delivering fuel?

 

[JonathanLingham]

View attachment 77208 View attachment 77208 View attachment 77208 View attachment 77208

I'm not 100% sure but if you don't have shut down valve, there may not be check valve at all (my OM612 has both, only pump I have opened myself).

Have you made leak back test, is aux pump delivering fuel?

Thanks for getting back to me. I've just been out to have another play (light better today) and managed (a) to take a photo which shows there is a valve there, held in with a circlip (just like in your photo) AND (b) gently press the valve in to make sure it works (it does). The hole in the return surprised me...I resume that’s supposed to be there?

I’m pretty sure the lift (auxiliary) pump is working...it moves the bubbles down towards the HPP when the engine is cranked...they then drift back up when I stop cranking. I was going to change the seals on the pipes entering the HPP while they were out, but I’m not sure the ones I got on eBay are the right ones...they look too "round”. The one on the pipe seems flatter.

 

[mersum1es]

oh those o-rings are flattened due to age... they should be round. Surely new seals will help keep the air out better. But it does not matter if injectors are leaking too much fuel to tank line, I suggest it will be you next action if new o-rings won't help.

 

[JonathanLingham]

View attachment 77208

Thanks for getting back to me. I've just been out to have another play (light better today) and managed (a) to take a photo which shows there is a valve there, held in with a (just like in your photo) AND (b) gently press the valve in to make sure it works (it does). The hole in the return surprised me...I resume that’s supposed to be there?

I'm not 100% sure but if you don't have shut down valve, there may not be check valve at all (my OM612 has both, only pump I have opened myself).

Have you made leak back test, is aux pump delivering fuel?

oh those o-rings are flattened due to age... they should be round. Surely new seals will help keep the air out better. But it does not matter if injectors are leaking too much fuel to tank line, I suggest it will be you next action if new o-rings won't help.

I suspect that the "O" rings I’ve bought are not for this position...137s rather than the 161s in the above diagram. They look a little small. I also need the squishy white 164s, as both are damaged (even though I’ve been told they do not actually do much).

 

[Doggysitter]

I had a problem similar.
Replace the o rings and the white foamy thing on the high pressure pump. If any air gets in through there it wont start. Also make sure the fuel filter has not run dry and airlocked the fuel lines.

One more thing to check is that the little lift pump above the high pressure pump is ok. I used an electric drill on the lift pump to draw the fuel up and replaced the pump when I was done. Mind you dont damage it though!

Good luck

 

[JonathanLingham]

I had a problem similar.
Replace the o rings and the white foamy thing on the high pressure pump. If any air gets in through there it wont start. Also make sure the fuel filter has not run dry and airlocked the fuel lines.

One more thing to check is that the little lift pump above the high pressure pump is ok. I used an electric drill on the lift pump to draw the fuel up and replaced the pump when I was done. Mind you dont damage it though!

Good luck

Thanks. I’ve now replaced the "O" rings on: the two pipes going into the high pressure pump; the inlet to and outlet from the low pressure (lift) pump above this; and the outlet from the filter. Lots of bubbles visible in the vertical pipe leading down from the LPP after I’d done this, of course, but I’ve managed to clear all of them with a fair bit of churning (I needed to recharge the battery a couple of times overnight to achieve this)...so fuel is obviously flowing.

So far so good. BUT the blanking thing still won’t start! And I can’t get rid of the "EPC" message on the dash. About to throw the towel in...I’ve arranged for the car to be towed to a specialist garage next Wednesday, to see if they can sort it out.

 

[Dagur]

Thanks. I’ve now replaced the "O" rings on: the two pipes going into the high pressure pump; the inlet to and outlet from the low pressure (lift) pump above this; and the outlet from the filter. Lots of bubbles visible in the vertical pipe leading down from the LPP after I’d done this, of course, but I’ve managed to clear all of them with a fair bit of churning (I needed to recharge the battery a couple of times overnight to achieve this)...so fuel is obviously flowing.

So far so good. BUT the blanking thing still won’t start! And I can’t get rid of the "EPC" message on the dash. About to throw the towel in...I’ve arranged for the car to be towed to a specialist garage next Wednesday, to see if they can sort it out.

Late reply i know but i am having a similar problem what was the outcome?

 

[remi1989]

Thanks. I’ve now replaced the "O" rings on: the two pipes going into the high pressure pump; the inlet to and outlet from the low pressure (lift) pump above this; and the outlet from the filter. Lots of bubbles visible in the vertical pipe leading down from the LPP after I’d done this, of course, but I’ve managed to clear all of them with a fair bit of churning (I needed to recharge the battery a couple of times overnight to achieve this)...so fuel is obviously flowing.

So far so good. BUT the blanking thing still won’t start! And I can’t get rid of the "EPC" message on the dash. About to throw the towel in...I’ve arranged for the car to be towed to a specialist garage next Wednesday, to see if they can sort it out.

What was the problem in your case ? did you get the car up and running again, or what was the outcome and or solution ?