Fuel Injection Pump for Ponton 220SE

[Pawel66]

I have a kind request: could anyone kindly explain how this FIP works? It is (EP/ZEA2KL75R4), early two plunger FIP for Pontons 220SE.

I understand overall way of operation is similar to Pagoda's FIP, what I do not understand is:
- I see something similar to WRD device on the picture
- I also see part 11, thermostat - what is this thermostat for? I see in the engine that it just sticks out there, no hose connected to it. What does it do?

[PeterPortugal]

Pawel,

The thermostat (part 11) is shown so you can identify the part. It fits inside the tube shown on top of the FIP. This does have hoses connected to it.

Regards

Peter

[PeterPortugal]

Inside here Pawel

[wwheeler]

The two plunger pump is an interesting bird. I have both, the two and the six plunger. The two plunger pump has two plungers that inject three injectors at once. Basically, the fuel awaits in the manifold tube for the intake valve to open and then an air/ fuel mixture flows in. Because of this, the timing is not as critical as the six plunger. This injection process is similar to what I call throttle body injection and was common in the US in the 80 and 90s. I could be wrong, but I think the setup you have in this picture is the Ponton 220SE. The W111 220SE has a totally different throttle linkage setup. My understanding is that the two plunger doesn't create as much power as the six plunger, but it is less finicky.

So the the pump has two thermostats. One is for the coolant and similar to the early 230SL. I believe that is the picture (#11). It has the housing as shown on the pump and also similar. The second thermostat (just to the right of the WRD) is the air temperature and sticks up into the air cleaner (at least on the Ponton 220SE, not sure on the W111 220SE). The air thermostat moves almost imperceptibly. I guess they decided it was overkill and left it off on the six plunger. This pump also has a starting magnet (#10), although it is mounted on top. It also has a barometric compensator and can be seen down low in between the two thermostsats. You see a screw in the picture, the rest of that is further down. This compensator is not as adjustable and probably more difficult to determine if is working than the six plunger. Overall, the two plunger pump does not have as many adjustments (or shims) that is available to the DIY as does the six plunger.

Wallace

[Pawel66]

Wallace, thank you so much for taking the time and responding.

My confusion came partially from the fact that the part with no. 11 looks like the air thermostat (furthest right) and is described as thermostat "cold start and cooling water". I guess it is just the same as the air thermostat or looks same on the picture. But, if I understand correctly, part no. 11 goes inside the housing (seen furthest left) similar to Pagoda thermostat housing.

Then I understand that the air thermostat was adjusting air/fuel mixture slightly depending on the outside air temperature. But this adjustments were, as you say, very small.

Thank you again.

[wwheeler]

Yes, the #11 is the cooling water thermostat itself and fits into the housing. Both the air thermostat and the water thermostat are similar looking though. But the cooling water thermostat is hidden when installed in the housing where as the air thermostat can be clearly seen when the air cleaner is removed.

[Pawel66]

Thanks again!

[Benz Dr.]

Air temperature was not considered all that important on our cars but was brought back for the D jet systems used on the 3.5 and 4.5 V-8 cars that followed. There's probably a variation of this system on all new cars.

[Pawel66]

Good learning, thank you!