im not sure if this is relevant, but i had a similar problem with my metering head on my gti. it had blocked up and meant that fuel wasn't coming out.
we checked this by releasing one of the fuel lines to the metering head, turning ignition on, and hearin the pump prime, then fuel SHOULD come out of the metering head, this proved that fuel was going in, and when testing the other side of the metering head there was no pressure at all!
Good luck, and im sorry if that didnt help!