This manual covers the Mercury Outboard Engine models manufactured between 1977 and 1989, encompassing a wide range of horsepower from 45HP to 220HP. These engines are known for their robust engineering and reliability, designed to provide dependable performance for various marine applications. This comprehensive guide details the various configurations, including 2-stroke and V6 engines, ensuring you have the specific information needed for your particular model. The purpose of this manual is to provide detailed service and repair information for Mercury Outboard Engines. It offers easy, step-by-step instructions suitable for all skill levels, covering essential areas such as safety, tuning, maintenance, fuel systems, ignition, powerhead, electrical systems, trim/tilt, lower unit, remote controls, and starter systems. This resource is recommended for immediate repairs and routine maintenance, empowering owners and technicians to keep their engines in optimal working condition.