W108 250SE fuel injection problem

[julian]

Hi folks.
Trying to get a parked one owner 250SE going. Parked for a long time. Very well maintained. Crappy stale fuel+++++.
Issue is the fuel injection pump is hosing out fuel at the outlets all simultaneously and immediately floods if connected to injectors. I suspect the ball or pressure valve under each outlet is gummed up with junk fuel and stuck open allowing continuous flow.
I would like to remove these valves and have them ultrasonically cleaned. The factory tool is 000 589 62 33 00 though I would like to try another method that doesn't involve kidney donation or endless searching. It appears to be a fine thread (12 x 1mm ?) but this is an odd size.
Can anyone assist in either confirming my initial diagnosis and whether there is any alternative means of removing these valves?

Julian

[Bartman4800]

Trying to understand the problem

If you loosen all the injector lines, fuel would probably just flush out fuel because there is no resistance in the line (the injector is the resistance), and the electric pump builds up a base pressure that is not sufficient to open the injectors.

The ball valves will stop the fuel from running back, not running out.

If I was you, I would run some carburetor cleaner through the pump to remove gunk.
Have the injectors ultrasonically cleaned, some of them are probably stuck open.

M12 x 1 is not an odd size. Fine thread on connectors is quite common.

I would be careful to open up the pump myself unless I knew exactly what I was doing. These units are expensive to rebuild, but robust.

Here is an example by Kent, how to clean the pump: https://www.youtube.com/watch?v=TPyvJBSHxKI


Bart

[julian]

Thanks Bart. Might go back to pump school.
Some carb cleaner might be in order!
No one of the usual suspects in Adelaide seem to be able to help with some internal threads to get this out. Any ideas on sourcing such threads to make this tool?
See pic for an example of what I'd like to remove.

[Bartman4800]

I don't have intimate knowledge of these pumps, but that item does not look screwed in. If it was, the German designers would have made something to rotate it with.

That is probably stuck in the hole by gunk, or by the seals below it.

Mercmad near brisbane can probably tell you more about these pumps.


Regards, Bart

[Bartman4800]

Have a look here, very similar to your pump:

https://www.sl113.org/wiki/Fuel/Injection

[julian]

Thanks, one of many useful references out there.

[Bartman4800]

And here is a parts list of the pump, page 2 shows what is underneath the nipple you removed:

https://www.sl113.org/wiki/uploads/Fuel ... 0pumps.pdf

Regards, Bart

[CraigB]

Just a fresh set of eyes having only just seen this. Given the robustness of the pumps and that injectors commonly leak etc, given Bart's 'engineer' description of operation, would you not first suspect that it is the injectors letting this constant flow of fuel through and not holding against the base pressure? Easy to test and possibly clean injectors first. I used a place on Brighton Road, about half way between Glenelg and Brighton, Near that Honda car dealer - Dave potter? If still there they did a good job on some range rover ones for me and were a bit cheaper. Got the suggestion from a google search and some forum for fast, modified, japanese cars.... as i recall.

[julian]

Thanks Craig for chiming in. There is a place in Adelaide that I’ve been put onto that does work on old Bosch pumps. Damned if I could find the little slip of paper I wrote the name on at this moment.

To add a little clarity to the description of fuel leaking.

Ignition on, engine off, rear pump pressurised, there is fuel flowing from all 6 pump elements simultaneously!

Lines have been cleaned and pressures correct.

Will recheck and confirm this remains the running condition.

Thoughts?

The rack moves easily checked via the test port, so I’m thinking remove all the valve elements and have everything cleaned through the ultrasonic cleaner.

[Bartman4800]

Think we already talked about that

If you loosen all the injector lines, fuel would probably just flush out fuel because there is no resistance in the line (the injector is the resistance), and the electric pump builds up a base pressure that is not sufficient to open the injectors.

The ball valves will stop the fuel from running back, not running out.

https://www.youtube.com/watch?v=TPyvJBSHxKI


Bart