went out on my pontoon today and the eng ran great for 45 min. then it slowed as I was heading to ramp. I did not see water coming out the pee hole when this happened. Should I pull the water pump and inspect? The pee hole is clear. the mercury is a 40 HP 4 cyl. I think 1991. ser is OD054364. thanks for any help/ I do have a Seloc book