This document pertains to the Mercury Mariner 40, 45, and 50 HP 4-Stroke outboard engines, including the Bigfoot variant. These engines are engineered for reliable performance and are designed to meet the demands of various marine applications. Their robust construction and efficient 4-stroke operation contribute to their reputation for durability and consistent power delivery across their specified horsepower ranges. This comprehensive Factory Service Repair Manual provides detailed information essential for the maintenance, diagnosis, and repair of your Mercury Mariner outboard. It covers a wide array of systems, including electrical, ignition, fuel, powerhead, mid-section, and gear housing components. With step-by-step instructions, advanced troubleshooting guides, and numerous diagrams and photos, this manual equips owners and technicians with the knowledge to perform service efficiently, ensuring optimal performance and longevity of the engine while potentially reducing labor costs.