This workshop service repair manual covers the Mercury Mariner 3.0 HP Outboard motor. Designed for reliable performance, this water-cooled, carbureted outboard features a CDI ignition system and a manual recoil start. Its forward-neutral-reverse gearcase provides versatile operation for various watercraft. This manual is intended for all models and engines within this series, offering comprehensive information for maintaining and understanding this robust marine propulsion system. The purpose of this English-language manual is to provide detailed guidance on the service, maintenance, and troubleshooting of the Mercury Mariner 3.0 HP Outboard. It covers essential procedures, including common issues such as starting problems, idling difficulties, overheating, and lack of power. This resource is invaluable for owners, mechanics, and technicians seeking to ensure the optimal performance and longevity of their outboard motor through accurate and efficient repair and upkeep.