I had my 15hp johnson overhauled The motor runs fine,but after afew hours running gray sludge comes out the holes just above the cavation plate.This keeps going for afew days of sitting around.I run 50to1 oil,I have played with the lean and rich.I was told screw the lean and rich nob all the way in and go out 3 turns to start with.I am running out of degreaser to clean the trasom and motor everytime. It also stops peeing 4 or 5 times an outing.I fix that by sticking apaper clip in the hole.Steamy pressure comes out,then works fine.Whats up with that? I need some good advice. 