Clarification of how the full load diaphragm eccentric works - posted to another forum by old school:

The eccentric tapered pin that's attached to the diaphragm is the FUEL DELIVERY RATE pin. Now from above, looking down at the pump, almost to the bottom of the bore that the delivery rate pin came out of, is the bore that the trigger or action pin rides in. The linear axis or centerline of the action pin is parallel to the axis of the pump drive shaft, or the engine crank shaft. The movement of the delivery rate pin (down with increasing boost levels) allows the action pin (which by internal spring pressure is contacting it) to contact the increasingly smaller diameter. This allows the action pin to move rearward, which increases the fuel delivery rate. As a note: according to my books, and Bosch injection manual, the "stock" or base line for the diaphragm position is 12:00 as you look at the pump. In other words, the tick mark is toward the valve cover, for the normal setting. I have seen this not to be true on at least two trucks, one of which was on my own. If you look at the underside of the diaphragm, and can see where the eccentric would push the pin in deepest toward the front of the pump, that is the LEAST delivery rate setting. Consider that 12:00. I've found that rotating the diaphragm clockwise from that point to 3:00 is a good place to go. Depending on the injectors that are in, and your turbo boost, you may want to turn a little more.

Here is something that will set you straight every time when dealing with the AFC diaphragm. When you remove the cap, go ahead and put a reference mark on the rubber piece and part of the metal housing it is sitting in. Then very CAREFULLY, pull up on the rubber diaphragm and it will slide up. Look at how the shaft that the diaphragm is connected to is tapered towards the bottom. I refer to it as being cylindrical, but slightly off center. It has a "deep side" and a "shallow side". You want to position it so that the deep side (the one that will allow the pin that rides on the shaft, to move the most) to be oriented toward the front of the engine.

Now that everyone is thoroughly confused grab your tools and get to Work!!!!

MORE VE INFO CAN BE FOUND HERE..

 

OK


What is considered the fuel pin? Is it the rod that slides on the eccentric, or is it actually the whole eccentric setup?

 

As stated in the above ^^^