This manual covers the Mercury Mariner 70, 75, 80, and 90 HP outboard engines manufactured between 1987 and 1993. These 2-stroke, 3-cylinder engines are known for their reliable performance and are equipped with carburetion fuel delivery and an oil injection system. Designed for a range of marine applications, these outboards offer dependable power output from 70 to 90 horsepower, featuring both tiller handle and power trim (Design I & II, Single Ram) controls. This comprehensive Factory Service Repair Manual provides essential information for maintaining and repairing your Mercury Mariner outboard. It includes detailed step-by-step instructions, troubleshooting guides with fault symptom diagnosis, electrical system repair procedures with wiring diagrams, engine tuning, and information on the lower unit and gear housing. Additionally, the manual covers scheduled maintenance, fluid capacities, engine installation, attachments, and includes detailed illustrations for parts identification, ensuring you have the necessary resources for optimal engine care and performance.