This service repair manual covers Mercury Mariner outboard motors, likely from the 1980s to 1990s era. These 2-stroke, water-cooled outboard motors typically feature 2 cylinders and offer a power output range of 30-40 HP, utilizing a carbureted fuel induction system and CDI ignition. They are designed for marine propulsion, providing reliable performance for various boating applications. The manual details specific engine components, including the gearcase with its drive system and typical gear ratios, as well as starter types that may be manual or electric depending on the model. The purpose of this manual is to provide comprehensive guidance for the maintenance, repair, and troubleshooting of your Mercury Mariner outboard motor. It includes detailed procedures for essential tasks such as lubrication of the lower unit, specifying oil type and capacity, and correct fuel-oil mixture ratios. Information on recommended spark plugs, trim system operation, and technical specifications is also provided. This resource is intended for owners, mechanics, and technicians to ensure the optimal performance and longevity of the outboard motor through proper service and repair practices.