1986 Mercury 50 HP Outboard Manual

The 1986 Mercury 50 HP Outboard is a two-stroke marine engine featuring 50 horsepower output, electric start, remote control capability, thermostatically controlled cooling, CD ignition system, through-hub exhaust, and corrosion-resistant components. This manual covers operation, maintenance, troubleshooting, and specifications for proper care and optimal performance.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Operation 6. Maintenance Schedule 7. Fuel System 8. Electrical System 9. Cooling System 10. Storage & Winterization 11. Troubleshooting

Features at a Glance

Key components: 50 HP two-stroke engine, CD ignition, electric start, remote control system, thermostatic cooling, corrosion protection.

Feature	Description
Engine Type	2-stroke, 3-cylinder
Ignition System	CD (Capacitor Discharge)
Starting System	Electric start with manual backup
Cooling System	Thermostatically controlled water pump
Exhaust System	Through-hub exhaust
Gear Ratio	1.85:1
Fuel/Oil Mix	50:1 gasoline to oil ratio
Propeller	Standard aluminum 3-blade
Trim System	Manual trim with tilt lock
Control System	Remote control compatible

Installation

Proper installation ensures optimal performance and safety.

Mounting: Select appropriate transom height; ensure transom is strong enough to support engine weight.
Steering Connection: Connect steering cable according to manufacturer specifications.
Control Installation: Mount remote control box within easy reach of operator.
Electrical Connections: Connect battery with proper polarity; secure all wiring.
Fuel System: Install fuel line with primer bulb; ensure all connections are tight.

WARNING! Engine is heavy; use proper lifting equipment. Ensure mounting bolts are properly torqued.

First-Time Setup

Initial setup procedures for new installation.

Fuel Preparation: Mix gasoline with Mercury or TC-W3 certified oil at 50:1 ratio.
Priming: Squeeze primer bulb until firm to prime fuel system.
Battery Connection: Connect fully charged battery with positive to positive terminal.
Initial Start: Turn key to start position; choke if necessary for cold start.
Break-in Period: Operate at varying speeds for first 10 hours; avoid prolonged full throttle.

CAUTION! Always operate in well-ventilated area. Check for fuel leaks before starting.

Specifications

Horsepower: 50 HP at 5000 RPM
Displacement: 49.8 cubic inches (816 cc)
Bore x Stroke: 2.87 x 2.60 inches
Weight: Approximately 187 lbs (85 kg)
Full Throttle Range: 5000-5500 RPM
Fuel Capacity: Dependent on boat tank
Oil Type: Mercury or TC-W3 certified 2-stroke oil
Spark Plugs: Champion L77JC4 or equivalent
Alternator Output: 9 amp charging system
Gearcase Capacity: 22 oz (650 ml) gear lube

Controls and Operation

Understanding engine controls for safe operation.

Remote Control: Throttle/shift lever, key switch with choke, tilt/trim switch, emergency stop switch.

Engine Functions: Throttle control for speed adjustment, shift lever for forward/neutral/reverse, choke for cold starting, tilt/trim for optimal running angle. Always attach emergency stop switch lanyard to operator.

Starting Procedure: 1. Ensure gear in neutral. 2. Prime fuel system. 3. Turn key to ON. 4. Advance throttle slightly. 5. Turn to START position. 6. Release key when engine starts.

Maintenance Schedule

Regular maintenance ensures long engine life.

Interval	Service Required
Every use	Check fuel system for leaks, inspect propeller
20 hours or monthly	Check gearcase oil, inspect spark plugs
100 hours or annually	Change gearcase oil, water pump impeller
300 hours or 3 years	Replace fuel lines, inspect exhaust system
As needed	Grease fittings, corrosion inspection

Tip: Keep maintenance log for service records.

Fuel System

Proper fuel mixture and system maintenance.

Fuel Mix: Always use 50:1 gasoline to oil ratio with fresh fuel.
Fuel Filter: Replace annually or if contamination is visible.
Carburetors: Synchronize and adjust annually for optimal performance.
Fuel Lines: Inspect regularly for cracks or deterioration.
Storage: Add fuel stabilizer for storage over 30 days.

WARNING! Gasoline is highly flammable. No smoking during refueling.

Electrical System

CD ignition and charging system maintenance.

Battery: Maintain fully charged; clean terminals regularly.
Spark Plugs: Replace annually; gap at 0.030 inches.
Ignition Timing: Set at 4° BTDC at idle; 21° BTDC at WOT.
Charging System: Test output annually; should produce 9 amps at cruise RPM.
Wiring: Inspect for corrosion or damage; protect with dielectric grease.

Cooling System

Thermostatically controlled water pump system.

Water pump impeller replacement: Required every 2 years or 200 hours. Check tell-tale stream during operation - should be strong and consistent. Overheating indicates blocked water passages or worn impeller.

CAUTION! Never run engine without water supply. Always use flushing attachment for freshwater operation.

Storage & Winterization

Proper procedures for off-season storage.

Fuel System: Add stabilizer; run engine to circulate treated fuel.
Cooling System: Flush with freshwater; drain completely.
Gearcase: Check oil; replace if water contamination present.
Battery: Remove and store fully charged in cool, dry location.
Exterior: Apply corrosion protection spray; cover for storage.

Tip: Store in upright position to prevent oil migration.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel, spark, or compression issue	Check fuel supply, spark plugs, compression
Engine overheats	Water pump failure	Replace water pump impeller; check thermostat
Poor performance	Fuel system or ignition	Clean carburetors; check spark plugs and timing
No charging	Alternator failure	Test stator and rectifier; replace if faulty
Gearcase noise	Bearing or gear wear	Inspect gearcase; replace damaged components

Service: Contact authorized Mercury dealer for major repairs.

Parts: Use genuine Mercury parts for optimal performance and warranty.