i go back to your post 14.
control pressure higher than system P.
when i get something like that i look at what am "I" doing wrong.
when doing the pressures test, the return from the WUR goes through the pres reg.
could be stuck
PR, could be the opening is too small to let enough fuel through if the pump is putting out more fuel.
do the fuel system test.
fuel flow out of the fuel head and WUR fuel flow.