Not great with outboards and need some help. I have a late 70's mercury 4hp thunderbolt outboard. Bought it a week ago and it runs great except for (1) thing. While its running I noticed that no water is being pushed out the fresh water port (I guess you would call it that), but there is air being pushed out the strong enough for me to feel it on my hand, so the water pump must be working right? So no water coming out, but air yes, so I thought there must be a blockage. So I hooked up a hose to the bottom and turned the hose on (engine off) and water was pushed up and out the fresh water port. Any one have any ideas why water isnt being pushed out. Much appreciated, thanks everyone. Detcuse