Mercury Mariner 100hp, 115hp Outboard Motor 1988–1993 Service Manual (P/N OEM 90-13645-2)

This 495-page PDF is the official Mercury publication (OEM 90-13645-2) covering the 1988–1993 100hp and 115hp 4-cylinder, 2-cycle outboard models.

• 12 detailed wiring diagrams and 9 troubleshooting flow charts to accelerate diagnostic times in the workshop.
• Includes 4 specialized exploded-view diagrams of the entire fuel system.
• Features step-by-step procedures to avoid expensive dealer labor, covering water pump impeller replacement, carburetor synchronization, lower unit rebuilds, power trim maintenance, oil injection system checks, thermostat inspection, and ignition timing adjustments.
• Provides detailed mechanical breakdowns for cowl removal, throttle-shift linkage alignment, Ride-Guide steering cable lubrication, swivel pin greasing, tilt lock lever testing, and propeller shaft servicing.

Engine and Electrical Systems Scope

This documentation delivers a highly specific technical breakdown of the powerhead. It details critical specifications, including the exact piston displacement of 1720.9cc and cylinder bore diameters of 85.7mm.

For electrical diagnostics, mechanics will find precise reference values for the C.D. breakerless ignition system. You can quickly verify stator resistance, trigger coil voltage output, and spark plug heat range requirements without second-guessing. The guide maps out correct wiring harness routing and features specialized diagrams for models equipped with power trim, enrichment valves, and varying alternator outputs (ranging from 9 to 24 amperes). Working on marine outboard electrical systems involves high voltage and specific hazards. Always adhere strictly to standard workshop safety protocols and disconnect power sources before beginning any maintenance.

Maintenance and Technical Data Preview

Fluid capacities and torque settings for critical assemblies are highlighted throughout the manual to streamline routine maintenance and bench work. Having the exact factory clearances and shimming charts on hand acts as a crucial repair reference that eliminates diagnostic guesswork and prevents costly assembly errors. Cylinder head bolt torque values are clearly documented inside the engine assembly sections. Furthermore, an ignition switch continuity chart allows mechanics to isolate electrical faults efficiently. Quick reference data includes:

• Spark plug gap: Specified at 0.040 in. (1.0 mm) for the NGK-BPH8H-N-10 series.
• Gear housing lubrication: Requires 22.5 fl. oz. of fluid, with distinct service intervals provided for both fresh and salt water environments.
• Low-speed mixture screw: Preset to 1-1/2 turns out for 115hp models in the carburetor specifications table.

Note: This page serves as a comprehensive contents overview and technical data preview for the manual. It does not contain direct repair or diagnostic instructions.