Re: Fuel quantity etc.
dalek, I'd say you ought to explore the very beginning of this (very same) forum thread --
http://forums.tdiclub.com/printthread.php?t=45870&pp=100
Noting the Distributor Head ... Fuel Collar ... etc.
I don't claim to understand much about how this pump works.
But there are a lot of forum posts around the 'net, with information about this pump.
Better yet, look for the Bosch manual of the VE pump, from the 'net.
Here are a couple of links ... the first one I've verified does work (it's a 5.5 MB file, give it some time):
http://www.dieselbookmarks.com/bombers/VEPump.pdf
The 2nd source (of the same exact file) is still working (just takes a lot longer) --
http://www.teamkorhonen.com/~dbwarrior/peugeot/BoschFuelInjectionPumpTypeVE2.pdf
I don't know whether this document has also been stored in our pics.tdiclub.com server ... I just looked there, couldn't find it.
Also,
http://forums.tdiclub.com/printthread.php?t=238872&pp=100
(* Edit *)
And about the Needle Lift Sensor, it's shown on this page --
http://www.myturbodiesel.com/1000q_how_to/multi/TDInozzleFAQ.htm
Also, see here --
http://www.haywood-sullivan.com/vanagon/TDI/TDI_diagnostics.html
NOTE: In our TDIs we also have an engine Speed Sensor (which I believe is also the same as "Crank Position" sensor ... also called "crank angle" sensor?).
I'm guessing that this (ALH ... MkIV) type of TDI engine doesn't need a Camshaft position sensor.
Probably all it really needs (for control of the injection pump, i.e. timing) is the #3 Needle Lift sensor, and the engine speed sensor.
There's an Injection Quantity or Injected Quantity (IQ) adjustment, but I don't really know how it works.
Aside from the "Hammer Mod", there's a Requested fuel quantity, that the ECM manages.
If your needle lift sensor isn't working or isn't available to the ECM, I believe the engine runs all right but you're in limp mode.
Larry