This manual covers the Mercury Mariner 9.9 HP 2-Stroke outboard engine, manufactured between 1986 and 2003. Engineered for reliable performance, this water-cooled, gasoline-powered engine features a carburetor fuel delivery system and a CDI ignition. Its robust construction and straightforward design make it a dependable choice for various boating applications. Key operational features include an emergency kill switch and trim and tilt adjustment, contributing to user safety and control on the water. This Factory Service Repair Manual provides comprehensive guidance for owners, mechanics, and technicians. It details essential maintenance procedures, including lubrication, spark plug and fuel filter replacement, and gearcase oil changes, along with troubleshooting common issues such as carburetor and fuel delivery problems. The manual includes detailed step-by-step instructions for disassembly and assembly, diagnostic procedures utilizing basic tools, and essential wiring diagrams to facilitate effective repair and upkeep of your Mercury Mariner outboard.