last year every once in a while my 5kw westerbeke genset would smoke terribly , this only happened three or four times, other days it would run for hours flawlessly, it smoked so bad once it looked like the boat was on fire. then the next time it was fine???? the smoke was light blue or gray i dont think its an internal problem such as rings or seals could it be a choke/mixture problem anyone sseen this happen before???( p.s. the smoke was out of the exhaust )