This manual covers Mercury Outboard motors manufactured between 1966 and 1989. Designed for a range of applications, these outboard motors are known for their robust engineering and reliability. This comprehensive guide is intended for owners and technicians seeking to maintain and repair these powerful engines, which span horsepower ratings from 90HP to 300HP. This Factory Service Repair Workshop Manual provides detailed instructions, hundreds of pages of content, and numerous diagrams to facilitate all repair, servicing, and troubleshooting procedures. It is designed to be an indispensable resource, offering step-by-step guidance and exploded diagrams to ensure accurate maintenance and repair of your Mercury Outboard motor.