The restricting orfice is actually in the outlet protion fo the filter housing, but you are correct in that it is located farily high up in the housing. The filter should have oil in it, about 1 quart. If thw filter is empty, I would suspect a possible plugged supply line. On the pump, I'm concerned that perhaps the pickup isn't attached properly, or perhaps there's something amok internally in the pump itself. You chouldn't have to rev it to get pressure, it should come up pretty much right away, especially when cold.
