[Helmsy]

My bet is somehow you are measuring it wrong with the gauge or have a fault (as suggested by Mark) so I wouldn't adjust shims or WUR.

Is your gauge on the pressure side of the WUR line? I presume some gauges if you cocked it shut and the gauge was on the wrong side it wouldn't read correctly. Try swapping the connections from your gauge hoses to the WUR.

All you need to do is undo #2 in your picture and put your gauge in between the #2 connection with the gauge on the side where the fuel is coming from and cock it shut and open a few times and then leave it shut.