This Service Repair Manual covers the Mercury Mariner outboard motor, specifically the Mariner model with 100 HP and 115 HP variants from the First Generation, produced between 1988 and 1993. These 2-stroke, 4-cylinder outboard engines, featuring a 1730 cc (105.5 ci) displacement and a carbureted fuel system, are known for their robust engineering and reliable performance on the water. The CDI ignition and water-cooled systems contribute to their efficient operation, making them a dependable choice for various boating applications. This comprehensive manual provides essential information for the maintenance, repair, and troubleshooting of your Mercury Mariner outboard. It details critical procedures, technical specifications, and safety guidelines necessary for keeping your engine in optimal condition. Covering areas such as lubrication, recommended oil types, fuel-to-oil ratios, spark plug specifications, idle speed settings, and propeller recommendations, this guide is an indispensable resource for owners, mechanics, and technicians seeking to ensure the longevity and performance of their 1988-1993 Mercury Mariner 100 HP / 115 HP outboard.