1988 50 hp Mercury Outboard Manual

The 1988 Mercury 50 hp outboard motor is a reliable two-stroke engine featuring 50 horsepower output, electric start, power trim and tilt, 3-cylinder configuration, loop charging system, CD ignition, and thru-prop exhaust. This manual covers operation, maintenance, troubleshooting, and specifications for proper care and optimal performance.

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

Features at a Glance

Key components: 3-cylinder two-stroke engine, CD ignition system, electric start, power trim/tilt, thru-prop exhaust, water pump cooling.

Feature	Description
Engine Type	3-cylinder two-stroke outboard
Displacement	49.9 cu in (818 cc)
Bore x Stroke	2.95 x 2.44 in (75 x 62 mm)
Ignition System	CD capacitor discharge
Starting System	Electric with alternator
Gear Ratio	1.85:1
Trim System	Power trim and tilt
Exhaust	Thru-prop underwater
Fuel System	Dual carburetors
Oil System	Pre-mix 50:1 fuel/oil ratio

Installation

Proper installation ensures optimal performance and safety.

Select appropriate transom height for boat design.
Mount engine using correct mounting bolts and brackets.
Connect steering system and throttle/shift cables.
Install battery and connect electrical cables (red to positive, black to negative).
Connect fuel line with quick-connect fitting.

WARNING! Ensure transom can support engine weight. Use corrosion-resistant mounting hardware.

Operation

Starting and operating procedures for safe boating.

Pre-start check: Verify fuel, oil, and cooling water intake.
Prime fuel system: Squeeze primer bulb until firm.
Starting: Turn key to ON position, push in for choke if cold, turn to START.
Warm-up: Allow engine to idle for 2-3 minutes before accelerating.
Shifting: Pause in neutral when shifting between forward and reverse.

CAUTION! Always check for water discharge to confirm cooling system operation.

Specifications

Horsepower: 50 hp at 5000 rpm
Weight: 195 lbs (88.5 kg)
Shaft Length: 20 inches
Full Throttle Range: 5000-5500 rpm
Fuel Consumption: Approx 5.5 gph at WOT
Oil Ratio: 50:1 gasoline to TC-W3 oil
Spark Plugs: NGK BUHW or equivalent, gap 0.030 in
Alternator Output: 9 amp
Gearcase Capacity: 22 oz (0.65 L) 90W gear oil

Controls and Indicators

Key controls: Ignition switch, throttle/shift control, trim/tilt switch, choke, safety lanyard.

Instrument Panel: Tachometer, temperature warning light, oil alert (if equipped).

Operation: Turn key to start position (push for choke when cold). Use trim/tilt switch to adjust engine angle. Attach safety lanyard to operator. Monitor temperature warning light during operation.

Maintenance Schedule

Regular maintenance ensures longevity and reliability.

Interval	Service Required
Each use	Check fuel system for leaks, inspect propeller
20 hours/1 month	Check gearcase oil, inspect spark plugs
100 hours/6 months	Change gearcase oil, water pump impeller
300 hours/3 years	Replace fuel lines, check carburetor synchronization
Annual	Full system inspection, corrosion protection

Fuel System

Dual carburetor system requiring proper fuel mixture.

Fuel mixture: 50:1 ratio of unleaded gasoline to TC-W3 certified two-stroke oil.
Fuel tank: Use approved marine fuel tank with vent opened.
Fuel line: Connect with quick-connect fitting, prime with bulb until firm.
Carburetor adjustment: Idle mixture screws preset at factory; minor adjustments only.

Tip: Use fresh fuel and stabilize if storing more than 30 days.

Electrical System

12-volt DC system with CD ignition and charging capability.

Battery: Minimum 450 CCA marine starting battery.
Charging system: 9 amp alternator for battery maintenance.
Ignition: CD system with stator, switchbox, and trigger assembly.
Safety: Lanyard stop switch must be connected for operation.

WARNING! Disconnect battery before servicing electrical components.

Cooling System

Water pump impeller system for engine cooling.

Operation: Water enters through intake grilles, pumped through engine by rubber impeller, exits through tell-tale stream. Always verify water discharge before continuous operation.

Maintenance: Replace water pump impeller every 2 years or 200 hours. Inspect thermostat annually. Flush with fresh water after saltwater use.

Storage & Winterization

Proper storage procedures to prevent damage during inactivity.

Add fuel stabilizer to full fuel tank and run engine for 5 minutes.
Change gearcase oil and inspect for water contamination.
Fog engine through spark plug holes with storage oil.
Drain cooling system or use antifreeze for freezing conditions.
Store in vertical position with propeller removed.

CAUTION! Never store with fuel in carburetors; drain completely.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel, spark, or compression issue	Check fuel delivery, spark plugs, compression test
Overheating	Water pump, thermostat, obstruction	Replace impeller, check thermostat, clear water intakes
Poor performance	Fuel restriction, fouled plugs	Clean fuel system, replace spark plugs
No charging	Alternator, rectifier, wiring	Test alternator output, check rectifier diodes
Vibration	Propeller damage, mounting	Inspect propeller, check engine mounts

Service: Contact authorized Mercury Marine dealer for major repairs.

Parts: Use genuine Mercury replacement parts for optimal performance.