What does this hose connect to or do?

[brookie]

Hopefully a straight forward question but here goes! On my 1.9TD AAZ I have a rubber hose (small about 6mm diameter) going from the inlet manifold to what looks like a vacuum unit mounted over the rocker housing. This unit is then linked via a moveable rod to a lever on the injection pump.
As the hose comes from the inlet manifold AFTER the turbo would this not have positive pressure in it? Therefore, what is the component which I think is a vacuum unit and what is it trying to move (via the rod) inside the injector pump? I've never seen this rod move even when I really rev the engine.
I can't find anything on this in my Haynes Diesel Golf book or my Peter Russek Td handbook.
The truth is out there - please someone tell me!
Thankyou
Rob

[angry vanagon]

got any photos of the pipe?

[brookie]

Unfort not. It's just like your diesel bleed off hose,black rubber 3mm internal diameter. Asked a diesel blokey today and he seemed quite sure it's for the advance on the injector pump. I'll go along with that unless there's any better ideas!