The Mercury Mariner 30/40 Outboard is a robust two-stroke engine designed for reliable performance on the water. Featuring a two-cylinder configuration with a displacement of 46.0 cubic inches (753 cc), this engine offers power options of 30 HP and 40 HP. Its water-cooled system and CD ignition ensure efficient operation, while the carbureted fuel delivery system provides consistent power. Engineered for durability and ease of use, the Mercury Mariner is a dependable choice for a variety of boating applications, delivering consistent power and smooth operation. This Service Repair Manual provides comprehensive guidance for the Mercury Mariner 30/40 Outboard. It covers essential maintenance procedures, including recommended oil types, capacities, and fuel-oil ratios, as well as specifications for spark plugs. Detailed technical information, troubleshooting steps, and performance data, such as the wide-open throttle RPM range, are included to assist owners, mechanics, and technicians. The manual is designed to facilitate proper upkeep and repair, ensuring the longevity and optimal performance of your Mercury Mariner outboard engine.