This manual covers the Mercury Mariner 30JET HP and 40 HP outboard engines. These engines are known for their robust construction and reliable performance, featuring a 4-cylinder configuration and carbureted fuel delivery. The design incorporates a rewind starter, an oil injection system, and options for both power and manual tilt, with multiple designs available for trim and tilt functionality. Control can be managed via a tiller handle or co-pilot system, and the transmission utilizes an outboard lower unit with a jet drive. This comprehensive Factory Service Repair Manual in English provides detailed guidance for the maintenance and repair of your Mercury Mariner engine. It includes step-by-step instructions, illustrations, diagrams, and photos for various repair procedures. The manual covers essential areas such as electrical and ignition systems, engine fault symptoms, advanced troubleshooting, and recommended service intervals. It is designed to assist owners, mechanics, and technicians in effectively maintaining and repairing the engine to ensure optimal performance and longevity.