The Mercury Mariner, a first-generation model produced between 2002 and 2007, represents a robust and reliable marine engine designed for a variety of watercraft. This 4-stroke engine boasts a 150 horsepower output, delivered through an Electronic Fuel Injection (EFI) system and a Capacitor Discharge Ignition (CDI) for optimal performance. Its inline, water-cooled configuration, with a displacement of 2077 cc, ensures efficient operation across its recommended RPM range of 4500-5500. Engineered for durability and consistent power delivery, the Mariner is built to meet the demands of recreational and professional marine applications. This comprehensive Workshop Service Manual provides detailed guidance for the repair and maintenance of the Mercury Mariner engine. Covering a wide array of topics, including essential lubrication specifications, recommended maintenance intervals, spark plug and fuel requirements, and transmission gear ratios, this manual is an indispensable resource. It is designed to assist owners, mechanics, and technicians in performing routine servicing, troubleshooting complex issues, and ensuring the longevity and optimal performance of their Mercury Mariner engine.