This service repair manual covers the Mercury Mariner 30JET HP and 40 HP outboard engines, featuring a 4-cylinder configuration. These robust engines are designed for reliable performance and are built with quality engineering. The Mariner series is known for its durability and efficiency, making it a trusted choice for various marine applications. This comprehensive manual provides detailed information essential for maintaining and repairing your Mercury Mariner outboard. It includes step-by-step procedures for routine maintenance, troubleshooting common issues, and in-depth technical specifications. Owners, technicians, and mechanics will find the guidance necessary to ensure optimal performance and longevity of the engine.