Zero fuel pressure when running??

Hi guys and gals! I need a little advise from any K jet gurus out there please….

I've had my 83 GTI tin top for a little while now, in that time I've been working through all the usual issues with success!
The car has always driven really strongly, although it had rubbish cold start!

So a couple of weeks ago i started to investigate what the problem might me? I've tested the time out switch! OK! I've tested the 5th injector! OK! I've tested AAV! Faulty! so replaced with a good unit I bench tested before fitting! I have stripped and cleaned the WUR and rebuilt it with a new rebuild kit off eBay! Now the car starts first flick of the key!!! But sadly is undrivable So this morning I hooked up a fuel pressure tester and I can not get my head around the readings????
Start the car and the gauge reads zero fuel pressure??
Close the tap (even only half way) to check the system pressure and she stalls? instantly!!
With the engine off is the only time the fuel pressure gauge registers any pressure @ 40 psi which holds strongly which I know is telling me the the accumulator is working fine.
Now seeing the only part I've messed with on the fuel side is the WUR I've had it apart again and all looks good???I Don't know if the WUR rebuild kit had any faulty parts???Any sound advise would be great as this is the last hurdle and I really want to get out and enjoy my GTI.
Many thanks  Mark.

Hi mate, when the engine is cold, the bimetallic plate inside is in retract position so the diaphragm in the WUR is open to allow fuel to pass through to cause a reduction in the fuel pressure so the air sense lifts easily while the AAV causes additional air to suck the air sense plates for a leaner mixture. As the engine runs, the bimetallic plate in both the AAV and WUR begin to close and the mixture becomes leaner and the fuel pressure starts increasing.

I would check the following:

1. ensure the WUR is correctly installed and the bolt, washers holding the bimetallic plate is in correct position.
2. check you are getting power to the connector when ignition on…..this is power to the bimetallic plate.
3. check that the fuel lines to the WUR are correct position
4. test the WUR bimetallic plate…..I believe you test with an ohm meter. Check the Haynes manual for test procedure
5. hook the pressure gauge as per the Hayes manual…..when you start the car the pressure should gradually increase as the bimetallic plate deflects and closes the diaphragm (there should be a pin the bimetallic pushes into the diaphragm, make sure that not missing front the assembly)

BRINZ said

Hi mate, when the engine is cold, the bimetallic plate inside is in retract position so the diaphragm in the WUR is open to allow fuel to pass through to cause a reduction in the fuel pressure so the air sense lifts easily while the AAV causes additional air to suck the air sense plates for a leaner mixture. As the engine runs, the bimetallic plate in both the AAV and WUR begin to close and the mixture becomes leaner and the fuel pressure starts increasing.

I would check the following:

1. ensure the WUR is correctly installed and the bolt, washers holding the bimetallic plate is in correct position.
2. check you are getting power to the connector when ignition on…..this is power to the bimetallic plate.
3. check that the fuel lines to the WUR are correct position
4. test the WUR bimetallic plate…..I believe you test with an ohm meter. Check the Haynes manual for test procedure
5. hook the pressure gauge as per the Hayes manual…..when you start the car the pressure should gradually increase as the bimetallic plate deflects and closes the diaphragm (there should be a pin the bimetallic pushes into the diaphragm, make sure that not missing front the assembly)

Thanks BRINZ for your help but all sorted now

So what was wrong?
It may help others out if they search and find this thread..