Bring a old post post back to light as im having a similar problem. Basically on switch on boost gauge levels up to 0psi and remains there until switch off.
So I had a look in my engine bay for perished hoses as umpkin(hope ave spelt it right working from memory) suggested and i found my boost sensor but its a little silver box :S there was a thin rubber hose runs up and along the front of the bulk head. and runs all the way along until it connets to nothing heres some pics.
Heres my T connection this right?
Heres where the pipe ends the T connection ^ is to left hand side of my hand.
I cant see anywhere this connects to? is it ment to join onto the T connection? As umpkin said it connects to.... cant memba what it was, as well as the boost sensor.
Hope that explains it.