Normally I can work through these things but the logic of this pump and subsequent adjustments has me baffled. I need some help...

Background. My 240 blows clouds of smoke at 3200 feet and up. At sea level there is none. My conclusion is that the IP is delivering too much fuel at higher altitudes. (Sounds right I think)

So here we go.
There are three pics in this post. First is the IP diaphragm which is mounted on the back of the pump just in front of the throttle shaft and within this housing is a fitting which leads tot he banjo bolt on the intake manifold. Again logic tells me that this diaphragm in some sense measures the amount of vacuum created through the manifold, and compensates for the throttle position and in some small way altitude to pull on the rack within the IP to adjust the fuel flow.
If I pull this hose off the back of the pump the motor takes off! So this makes some sense to me...

The second picture is where the diaphragm attaches to the rack inside the pump. There is a minor adjustment to the compensating path here using spacers between the diaphragm and the attachment point to the rack... The adjustment on this is only 1.1 mm so I really don't know if this being off by say .01 mm would affect much but bear with me. On the left side of this photo is the attachment point for the bowden cable that shuts off the car. Now based on simple bowden cable theory it actually pushes on the lever which in relative terms pushes the rack to the back of the IP (picture view) to shutoff the flow of fuel hence killing the motor. I think I'm on this corrrectly... However the throttle as described below increases as it allows the rack to move backwards? I may have the shutoff theory backwards... Help...

The third picture in the series is the throttle housing which attaches to the back of the pump sandwiching the diaphragm between the main pump body and the throttle body. The throttle when engaged actually allows the rack to move towards the back of the pump as it is not directly connected but rather has a rotating point that is in contact with the center of the diaphragm and pushes it forward as the throttle is released or allows it to draw back as the throttle is depressed. What draws it back I have no clue. Vacuum? if so then why would the engine accelerate upon disconnecting the vacuum line? Wouldn't this in hteory allow the rack to move forward with no vacuum pulling on it? Now, in the third pic is a spring sticking up that has 5 shims under it within the throttle body and this spring mounts up against the diaphragm pushing on it constantly from teh back of the pump.

Okay, obviously I am totally confused on this subject. I believe that based on the smoking I need to reduce fuel at this altitude. But I cannot for the life of me figure out which adjustment I would make. Is it the shims under the spring (add or remove). Also I cannot seem to get the diaphragm to hold vacuum, partial yes but not "hold". I'm now beginning to think that it won't no matter since it is a leather like material.

I am open to a phone call at my expense if someone can help me figure this out...
Thanks, the perpetually baffled Fisherman

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique