This workshop service manual covers the Mercury Marine Mariner outboard engine, specifically models produced between 2002 and 2005, with a power output of 30 horsepower. These engines are characterized by their 4-stroke design and Electronic Fuel Injection (EFI) for efficient operation. Engineered for reliability and performance, the Mariner outboard is a robust choice for various marine applications, offering dependable power and advanced technology for its class. This comprehensive manual provides detailed information essential for the maintenance, repair, and overhaul of your Mercury Marine Mariner outboard. It includes crucial technical specifications, routine maintenance procedures such as fluid changes and spark plug replacement, troubleshooting guidance, and information on the engine's cooling, electrical, and propulsion systems. Whether you are a boat owner, a professional mechanic, or a technician, this manual serves as an indispensable resource to ensure your engine operates at peak performance and longevity.