Right so to confirm,
The flap moves up and down no issues with very little resistance?
When you manually lift it up, you get fuel from the injectors?
The plate(disc) is now level with the upper portion of the metering unit?

If so, fuel pressure really does need to be tested and if that turns out fine, then its likely got to be a massive vaccum leak meaning the disc isnt actually being lifted (through vacuum) when the engine is cranking.
If you've got all the time in the world this is fine, but in honesty this is the kind of thing that could be solved in about 30minutes by someone who knows the system as was standing in front on the car. Dont know if youve got any local groups or a friendly garage who could help out for a few beer tokens.