Regarding the manual stating that after 30 minutes it can bleed down to 36p.s.i., I believe this is a misnomer. It is my experience (and that of other x-fire owners)that the check valve can and does bleed down to a few p.s.i. after time. It only takes a pound or two of pressure to hold fuel in the lines from backing up. Even though my fuel rail gauge from Needswings shows zero after time, I know it has at least a couple pounds in there, as it always starts right up.
Even only one pound of pressure equals about 27 inches of water column;that is about the height difference between the pump and the injectors(give or take).