W111: Checking installation of injection pump

[Stebuga]

Hello to all,
Mechanic that helped me in the past retired definitively and the new one made a good job refitting the engine on my 220 sebc but the problem is that now the car doesnt start. His doubt is that the previous mechanic didn’t install the injection pump properly. Do you know if it is possible to know if it is not installed properly without disassemble it? I found a topic here but the pump is different from mine 😞 (mine is the one with only 2 outs). And again, which is the right procedure to install the pump? I have seen that pistons 1 and 6 have to be at the TDC but I didn’t understand well which part of the pump I have to align with the mark on the engine.
Thank you for helping!
Stefano

[Pawel66]

I came across this when I was looking for hints for W112:

https://www.sl113.org/forums/index.php?topic=18030.msg125664#msg125664

maybe it is helpful.

[Stebuga]

Thank you Pawel, I saw this one: it is very clear when he tells that, first, we have to place piston 1 and 6 at TDC, but I do not understand exactly which is the mark on the pump that I have to align with the one on the engine. A photo or a drawing could greatly help!

[wwheeler]

The 220SE has the two plunger pump and the 250SE and up has the six plunger. Totally different beast and are also timed differently. The two plunger pump only has two pistons.

That being said, timing is of little concern with a two plunger pump because of the way it works. It fires three injectors at once and the fuel sits in the manifold until the intake valve opens up. If you look how it is plumbed, one line from the pump goes to a block and is then distributed to three injectors. So two lines each supplying three injectors gives you six cylinders. If it is waaaay off, then maybe you might have an issue.

I might look elsewhere for the starting issue. Cold start valve, throttle linkages, etc. Has it ever run since the pump was installed? I have a picture somewhere of the timing marks for the 220SE pump if you want. And do know that it is installed at TDC which is different from the six plunger pumps.

[Stebuga]

Thank you Wwheeler,
Car runned when I buyed it, then I started a restoration, including a complete refurbishent of pump and injectors. Now, at the injectors come only little fuel, so I thought that pump is not correctly installed. Always a problem when someone begins and another one has to end a work! 

[Pawel66]

Have you checked the FIP-injectors fuel lines? If you plated them - they get clogged very often!

[wwheeler]

When you say only a little fuel at the injectors, do you mean at the tip of the injector or in the fuel line going to the injector? The injector only sprays a tiny amount, but the fuel line should supply a generous amount. Fuel line could be clogged as Pawel says. The timing would have nothing to do with the amount of fuel getting to the injector. You might need to look at a lot of things including the fuel pump volume, make sure filters are clean, make sure tank screen is clean and the list goes on.

You can do a fuel pump volume test at the return line. It should pump 1 liter in 15 seconds. If it doesn't, that could be a problem also. Maybe start with easy things first.     

[Pawel66]

Maybe start with easy things first.   

Exactly!

As an amatuer weekend mechanic I learned it already what experienced fellow members kept repeating: do not shoot from the hip, source the issue as per sequence - you will save time in the end. There is a chain of elements that need to work before fuel gets to line and then injector in the end (and indeed you would be surprised how little fuel goes through injector).
Fuel delivery test is easy - just undo the return hose at the pump side and mesure volume (yes, there are sophisticated techniques - you need to start measurement when the pump worked for some minutes).

If this stage is ok and your observation is little fuel at the end of the line - I would first check the line.

[Stebuga]

Fuel from electric pump ok, I measured 1 lt in little more than 15 sec, instead, fuel at the injection pump out seems only a little, same amount that at the end of the 2 primary lines.
I have a little video but dont know how to post it: maybe a wetransfer link?

[ja17]

Stebuga, it takes a lot of cranking of the starter to prime those long injection lines. Try energizing the cold start solenoid on the intake for an instance to see if the engine fires. If so, then your injection lines may not be fully primed with fuel. My advice for starting is, remove all spark plugs, loosen the injector lines at each injector and crank engine at full throttle. As fuel emerges from each loose injector connection, tighten it and repeat until all lines are primed and tightened. Install all spark plugs and start engine!

[Stebuga]

Thank you Joe, nice procedure! Here the video of injector pump outs: all ok or not enough fuel flow?
https://youtu.be/myDkJt971gQ

[ctaylor738]

Uhh, have you put a timing light on cylinder #1 to make sure you have spark at the correct firing point?  Probably just before TDC when cranking the starter.