Below is a rough translation of how to rebuild a renault 1.6L diesel injection pump. The original post is from this French site: http://www.forum-auto.com/pole-technique/section12/sujet293129.htm I take no credit for the original pictures or text but have added some notes as how they apply to VW. If you have a better translation, please post in the forums.
Add the center spring
Then the disc cover with cam plate. The teeth fit into the empty grooves.
The pin on the backside of the cam plate must face like so:
The cams (bumps) of this disc while passing on the rollers is what moves the piston and compresses the fuel and the injection. The original author had swapped the disc from another model car with a slightly different cam profile. The pin on the back of the cam plate fits into the groove shown on the piston below. The original author marked a hole in green but if you follow the hole down you can see where the pin sits.
The piston distributor hole:
The regulator: on VW TDI, this moves back and forth to "throttle" the fuel using a solenoid. On non TDI and older pumps, pressing the accelerator pedal moves this manually with a lever isntead.
This ring, directly actuated by the regulator, will more or less, cover the exhaust hole of the piston (located in the previous photo). During the injection, cam moves, moving the piston. The regulator position controls the proportioning of the amount of fuel injected. When the hole is open, the pressure is released and the injection stops. The piston is known as the distributor because during rotation, it directs the fuel towards one or the other of the exits of the pump. Each exit goes to 1 fuel line and 1 fuel injector.
Reassemble the piston distributor:
then return springs:
The washer at the end of the piston:
The put the whole thing in the pump:
Now reassemble the regulator levers and their return springs. TDI use a solenoid instead of manual regulator levers.
the difficult part of this is due to the position of springs:
Close up of the articulation of the levers by special bolts (custom to the modifications by the original author)
installation of these bolts with their new aluminum joint
"Y' has more than A returns the whole of the levers speaks high" (couldn't translate this part)
The piston distributor (exhaust port marked w/green arrow), the opening for the injectors (red), and the 4 grooves for filling the chamber (green circle).
All the return springs in place
I had difficulty translating this part but I believe it said that the original author had to try it a few times to get it back with all the springs still in their correct position. If the springs don't fall into place then you must redo it.
All the pieces of the centrifugal governor.
The pieces of the masselotes.
Placed into the body of the regulator.
Replace the sleeve of the regulator (notice the gauged hole to modify the beginning of injection according to the load):
Alignment of the axis of the regulator in the pump housing
The spacers which go behind the rotor of the regulator.
Then the regulator.
Then tighten the axis using a key. Use this special wrench to counter hold the axis during tightening. The position of this axis is important, because it regulates the the beginning of injection according to vacuum load. Therefore, you must have marked it during disassembly to get the same alignment.
Removal of the lever bushing
A new bushing
Securing the bushing with a bolt and washer
The control shaft and the regulator springs
The flat part (green) is engaged in the notch of the lever (red)
Put back the lid (with its new joint) and screw it in place.
Reassemble the stick control, note the exact position before disassembly.
The regulator valve and new components
The fuel shut off solenoid (exact same as VW TDI)
And finally the main shaft front seal, you have to gently press it in with a drift or socket.
Search the site for VW TDI specific information: