My 93 mercury 40hp will idle all day long with a water hose on it in the yard, but it doesn't idle long in the water. It acts like it has more of a load on it just being in the water. Do you think I need to replace my impeller on my water pump. I was also wondering where can I buy new carbs for the same motor. I can't find new ones anywhere on the web. If I don't eventually get all the little bugs worked out I'm going to buy brand new ones or get another motor.