Friday morning my injector pump began leaking between the main pump body and the distributor housing.
I replaced the O-ring seal by:
1. Remove fuel lines
2. Remove throttle cable and cold start cable
3. Remove the cold start bracket
4. Remove the fuel stop solenoid
5. Back out the 4 distributor head bolts until the O-ring was just visible
6. Hook the old o-ring (VERY cracked), cut and remove
7. Remove the top closer bolt and place a soda straw shim over it and replace it (prevent new O-ring from snagging on threads).
8. Remove all the other distributor head bolts (leaving the shimmed bolt in)
9. Stretch new O-ring over the head and get into the grove
10. Replace the 3 non-shimmed bolts
11. Hook the new O-ring and remove the shimmed bolt, allowing the o-ring into the groove.
12. Replace that bolt and begin tightening.
13. reverse order from 5 to 1.
14. primed fuel pump by applying vacuum until no air was visible in line
15. Crank it up and !!!!
No fuel coming out of the pump.
I checked the solenoid, it draws ~1.6amps and has an audible click. I removed it and there is diesel in the hole, and the plunger moves freely. I loosened the lines at the fuel injectors and am not getting any flow.
Did I miss something???
-Photos to come.
-Scott

Curious as to what the function of the "What is this?" solenoid is, it draws no power and has 0v at key on, while the fuel cutout obviously turns on.
-Scott
I'm wondering the same thing. I'm swapping in an aaz into an a2. does the "what's this" have to be hooked up.
that is that NOx reducer. it is purely an emissions device. it reduces NOx emissions by retarding the engine.
apply 12V supply to it from the stop solenoid and enjoy a little bit more power down low.
Did I miss something???.
-Scott
I'm guessing the answer is "yes".. unless I misread your description.
Common practice is to remove the timing bolt, insert a longer bolt or a piece of a thinner bolt, and then use the longer bolt (or original bolt) to hold the fuel plunger in place... slowly turning in the inner bolt while loosening the 4 surrounding bolts.
Otherwise there's a really good chance the cam rollers will loosen and drop into the bottom of the pump... best case they just stay there, worst case they jam against something... either way no plunger, no pumping.
If the above is the case your pump will need to come out of the car and be fully disassembled... without using the center bolt trick gravity is your enemy and proper alignment of the internal parts is very very difficult.
Here's a thread on the subject:
http://www.vwdieselparts.com/forum/viewtopic.php?t=5311&postdays=0&postorder=asc&start=15
That is what I was afraid of that something in the pump fell out of place. I have a friend who will be letting me borrow the timing tools in about a week when I see him next so I guess I'm going to pull the pump.
I'll post pics of the guts when I get it apart.
-Scott
gravity can be your friend ... one slight mod ... put the pump over a hole in a box (or put in a vise) with the high pressure pump UP ..... gravity will keep the little bits aligned inside while you change the O ring ... worked for me...