W108 1968 250SE fuel injection system

[zdzich]

I have a 1968 250SE W108 with a mechanical fuel injection system and I can't get it to work. Looks like there is nothing coming out of each injector. The electrical fuel pump is new and delivers enough fuel to the injection pump. I disconnected injector lines from the injection pump and have some fuel shooting up when I crank the engine. Does anyone know what should be the fuel pressure in fuel lines going to each injector ? Maybe my injection pump doesn't provide the right pressure for the injectors ? Thank you.

[wwheeler]

There are so many things to go wrong here but here is a place to start. This is the same system as the 113, so search the site. There are many posts that deal with this. What is the history with the injection pump?

Are you getting fuel out of all 6 ports on the injection pump? If you put the lines back on the pump and disconnect the lines at each injector, are you getting fuel out of the fuel lines lines at the manifiold? It is best to bleed the fuel lines at the injector when removing the lines at the pump.

Make sure your filters are clean. You can do a flow and pressure test for the rear fuel pump. With clogged screens and filters, even a new pump won't work properly.

You also might confirm the torque on the injection pump fittings that contain the check valves. Again, search the site for this.   

[ja17]

Sounds like the rack is stuck in the injection pump.  Remove the 10mm round cover on the front of the pump and thread in a screw and try to move the rack back and fourth. Get back with us for the next steps to follow. Most likely we can get you on the road!

[zdzich]

thank you to both of you for your suggestions. finally, I got it to work. I think that because the car wasn't running for many years the injection pump needed some time to start working. I installed electronic ignition which improved the spark and the engine is working now. Thanks again

[zdzich]

Can anyone tell me please at what pressure the fuel injector should open ? Fuel injector by Bosch DC8C45R1. Same car, 1968 250Se with M129 engine. I couldn't find any specifications for this injector. Thank you.

[wwheeler]

Call Gus at Pacific Fuel injection. Number should be in the Vendor file.

[zdzich]

Thank you. Would you know by any chance the part number for the Bosch distributor ? A picture would also be very handy. Thanks again.

[mbzse]

.../... at what pressure the fuel injector should open? Fuel injector by Bosch DC8C45R1

A worn injector should open at [min] 15kg/cm2  A new one at 18kg/cm2
/Hans in Sweden

[zdzich]

Thank you Hans, I just installed 6 new injectors. The old ones were leaking and the pattern was bad. Now I have a problem with the distributor. The one I have has the Bosch part number 0231142003 and I don't know if this is the right one. This distributor came with the car when I bought it a year ago. Would you know if this is the correct distributor ? The car is a 1968 Mercedes 250SE with engine 129.980 serial number 12-049605.

[mbzse]

.../... Would you know if this is the correct distributor ? The car is a 1968 Mercedes 250SE with engine 129.980 serial number 12-049605

See diagram attached for designation. However, nowadays I install electronic distributors (123 type Mercedes-6-RV) only.
/Hans in Sweden
.

[zdzich]

Thank you Hans. Any recommendations for such electronic distributor ?

[mbzse]

just google it
for instance manufacturers web: http://www.123ignition.nl/products.php
Lots of postings in this Forum as well
/Hans in Sweden

[wwheeler]

I have the 123 on my '68 W111 and has been working flawlessly for about 5 years now. Good investment if your not a strict purest. Few would notice the difference between it and the original.

[zdzich]

Thanks to both of you