This manual covers the Mercury Mariner 90 HP 3 Cylinder Outboard, manufactured between 1987 and 1993. These robust engines are known for their reliable performance and efficient design, featuring a carbureted fuel system and oil injection for optimal lubrication. The engineering quality ensures durability for a wide range of marine applications. This Service Repair Workshop Manual provides comprehensive guidance for maintaining and repairing your Mercury Mariner outboard. It includes detailed procedures for routine maintenance, troubleshooting diagnostics, electrical system wiring diagrams, and information on components such as the powerhead, transmission, and trim systems. The manual is designed to assist owners and technicians in keeping the engine in optimal condition.