This Service Repair Manual covers the Mercury Mariner 4 HP outboard motor. This water-cooled, 4-stroke engine utilizes a CDI ignition system and carburetor fuel delivery, offering 4 HP of reliable power. It features a manual recoil starter and an outboard gearcase with Forward, Neutral, and Reverse gears, designed for dependable operation. This manual provides comprehensive guidance for the maintenance, repair, and technical understanding of your Mercury Mariner 4 HP outboard motor. It details essential procedures, including engine oil changes, lubrication, spark plug specifications, and cooling system maintenance, alongside technical specifications and troubleshooting information. This resource is designed to assist owners and technicians in ensuring the optimal performance and longevity of the vehicle.