i have 20 horse power yanmar 3GMF motor. in neutral i can get the rpms up to 3500-4000 if i wanted, however when i put it into gear the highest i can go is about 2000. when i go above that i get heavy black smoke from the aft thru hull. no smoke in cabin or engine compartment. is this an exhaust mainfold problem or maybe a saltwater cooling problem? thank you for any help you can give.
wow..jsl3 sounds like we had the same problem.....i scraped the bottom in june. looks like im going back down this weekend...what did you use to scrape..spackle knife? is there anything better......really would like to do this in the water