The Mercury Mariner Marathon series outboard motor, featuring a 55 HP 2-stroke engine, represents a robust and reliable option for various marine applications. This water-cooled motor, with its 3-cylinder configuration and 89.5 cubic inches of displacement, is designed for efficient operation. Its carbureted fuel induction system and CDI ignition ensure consistent performance, while the typical 2.15:1 gear ratio in the gearcase is optimized for power delivery. This outboard motor is engineered for durability and dependable performance on the water. This Service Repair Manual provides comprehensive guidance for the maintenance and repair of your Mercury Mariner Marathon outboard motor. It covers essential procedures, technical specifications, and troubleshooting steps necessary to keep your engine running optimally. Inside, you will find detailed information on routine service, including recommended oil types, fluid capacities, spark plug specifications, and fuel mixture ratios, as well as guidance on electrical and fuel systems. This manual is an indispensable resource for owners, technicians, and mechanics seeking to ensure the longevity and peak performance of their Mercury Mariner outboard motor.