I recently bought a pontoon with a 1996 25hp mercury.
Motor starts but no water came out hole.
I shut off immediately. Replaced water pump impeller. Still starts fine
but no water out of hole, only some blue smoke. There appears to be some
bubbling coming up from prop area while motor is running.
I blew thru lines prior to replacing impeller. Motor has spent a fair
amount of time with lower unit in water. There was some scum on leg. This
motor has been fresh water use only.

Any ideas????