ok so i have a 95 merc outboard 50hp and i changed the impeller/water pump and it would blow air but not water. a man on the water or dock bc i never really made it to the water just off the trailer but he told me i had it upside down!!?? so my question is how do you tell which way the impeller is supposed to be in which side is up or down and what direction the "fins" face?? any help would be appreciated thanks.