This workshop service manual covers the Mercury Mariner 100 HP outboard motor manufactured between 1988 and 1993. This engine is a 4-cylinder, water-cooled, gasoline-powered unit designed for marine propulsion, delivering 100 horsepower. Its robust construction and reliable performance have made it a trusted choice for various boating applications. The outboard lower unit features forward, neutral, and reverse gears, providing versatile control on the water. This comprehensive manual provides essential information for the maintenance, repair, and servicing of your Mercury Mariner 100 HP outboard. It details procedures for routine maintenance, troubleshooting common issues, and performing in-depth repairs. Included are technical specifications, electrical system information, and guidance on the cooling and fuel systems. This manual is an indispensable resource for owners, technicians, and mechanics seeking to ensure the optimal performance and longevity of their Mercury Mariner engine.