This Service Repair Workshop Manual covers Mercury Outboard Engines manufactured between 1977 and 1989. These engines, known for their robust engineering and reliability, offer a wide range of horsepower options from 45 to 220, catering to various marine applications. They feature 2-stroke technology, with fuel systems ranging from carbureted to electronic fuel injection (EFI), and utilize water-cooling systems. Ignition systems vary by model, including points, CD, and electronic ignition. The extensive range of engine variants ensures a suitable option for diverse boating needs, reflecting Mercury's commitment to performance and durability in marine propulsion. This comprehensive manual provides detailed guidance for the maintenance, repair, and troubleshooting of your Mercury Outboard Engine. It includes step-by-step instructions, zoomable illustrations, exploded views, and component breakdowns to facilitate understanding and execution of tasks. Key areas covered include safety procedures, engine tuning, routine maintenance, fuel and oil systems, ignition timing, powerhead, electrical systems, trim and tilt mechanisms, lower unit servicing, and remote control adjustments. Designed for both DIY enthusiasts and professional technicians, this manual is an essential resource for ensuring the optimal performance and longevity of your Mercury outboard motor.