Product Manual

ManualsBrandsMercury Marine ManualsMarineMercury 20 HP (20") Shaft EFI Outboard Motor

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Table Of Contents

Notice to Users of This Manual
Precautions
Replacement Parts
Cleanliness and Care of Product
Copyright and Trademark Information
Manual Outline
Section 1A - Specifications
- Table of Contents
- Model Specifications
- Ignition Specifications at 20 °C (68 °F)
- Charging and Starting Specifications
- Fuel System Specifications
- Cylinder Block/Crankcase Specifications
- Piston Specifications
- Cylinder Head Specifications
- Oil System Specifications
- Cooling System Specifications
- Power Tilt Specifications
- Gearcase Specifications
Section 1B - Maintenance
- Table of Contents
- Cleaning Care
  - Do Not Use Caustic Cleaning Chemicals
  - Cleaning Care for Top and Bottom Cowls
    - Cleaning and Waxing Procedure
- Inspection and Maintenance Schedule
- Battery Inspection
- Flushing the Cooling System
- Fuel System
- Fuse Replacement - Electric Start Models
- Spark Plug Inspection and Replacement
- Timing Belt Inspection
- Engine Oil
- Corrosion Control Anodes
- Propeller Replacement
  - Removal
  - Installation
- Gearcase Lubrication
- Lubrication Points
- Storage Preparation
Section 1C - General Information
- Table of Contents
- Recording Serial Number
- Model Year Production Code
- Engine Component Identification - Manual Start Model
- Engine Component Identification - Electric Start Model
- Following Complete Submersion
- Fuel Requirements
- Painting Procedures
- Emissions
- Shipping of Hazardous Material (HazMat) and Engine/Components Containing Hazardous Material
Section 1D - Outboard Installation
- Table of Contents
- Start in Gear Protection
- Lifting the Outboard
- Installing Outboard
  - Boat Transom Height Requirement
  - Installing Outboard on Transom
- Steering Cable Installation
- Steering Link Rod Fasteners
- Remote Wiring Harness and Control Cable Installation
- Battery Installation
  - Mounting Battery
- Battery Connections
  - Connecting Outboard Battery Cables
  - Disconnecting Outboard Battery Cables
Section 1E - General Troubleshooting
- Table of Contents
- Conditions Affecting Performance
- Compression Check
- Cylinder Leakage Test
  - Analysis
- Guardian Protection System
- Warning System
- Troubleshooting without a Computer Diagnostic System (CDS)
- Troubleshooting with CDS G3
- Accessing ECM Information with CDS G3
- CDS G3 Screens (10/15/20 EFI)
  - CDS G3 Live Data Screen
  - CDS G3 Diagnostics Screen
- Engine Control Module Pinout
- Fault Codes
Section 2A - Ignition
- Table of Contents
- Ignition Specifications at 20 °C (68 °F)
- Ignition Theory of Operation
- General Troubleshooting
- Engine Control Module (ECM)
- Wire Color Code Abbreviations
- Sensors
- Ignition Components
Section 2B - Charging and Starting Systems
- Table of Contents
- Charging and Starting Specifications
- General Troubleshooting
- Starter Motor Components
- Starter Motor and Solenoid Electrical Components
- Wire Color Code Abbreviations
- Charging System
- Starting System
- Starter Motor
Section 3A - Fuel System Operation
- Table of Contents
- Theory of Operation
- Engine Control Module (ECM)
- Sensors
- Actuators
Section 3B - Troubleshooting and Diagnostics
- Table of Contents
- General Troubleshooting
- Testing Fuel System Inlet Vacuum
- Fuel Pressure Test
- Wire Color Code Abbreviations
- Fuel System Wiring Diagram
- Sensor Wiring Diagram
Section 3C - Service Procedures
- Table of Contents
- Fuel System Specifications
- Fuel System Components
- Vapor Separator Tank Components
- Air Intake Components
- Fuel Lift Pump
  - Fuel Lift Pump Removal
  - Fuel Lift Pump Installation
- Vapor Separator Tank (VST)
- Camshaft Gear Cover/Vent Tank
  - Removal
  - Installation
- Throttle Body
  - Throttle Body Removal
  - Throttle Body Installation
- Fuel Rail
- Air Box
  - Air Box Removal
  - Air Box Installation
- Idle Air Control (IAC)
Section 4A - Cylinder Block/Crankcase
- Table of Contents
- Cylinder Block/Crankcase Specifications
- Piston Specifications
- Cylinder Block and Crankcase Components
- Crankshaft Components
- Powerhead Removal
- Cylinder Block Disassembly
- Powerhead Cleaning, Inspection, and Repair
- Powerhead Assembly
- Powerhead Installation
Section 4B - Cylinder Head
- Table of Contents
- Cylinder Head Specifications
- Cylinder Head Components
- Intake/Exhaust Valve Components
- Camshaft and Oil Pump Components
- Valve Adjustments
- Cylinder Head Removal
- Cylinder Head Disassembly
- Cleaning and Inspection
- Cylinder Head Assembly
- Cylinder Head Installation
Section 4C - Oil Pump
- Table of Contents
- Oil System Specifications
- Oil Pump Removal
- Oil Pump Disassembly
- Oil Pump Inspection
- Oil Pump Assembly
- Oil Pump Installation
- Oil Flow Diagram
Section 4D - Cooling System
- Table of Contents
- Cooling System Specifications
- Cooling System Description
- General Troubleshooting
- Thermostat
- Water Flow Diagram
Section 5A - Clamp/Swivel Bracket and Driveshaft Housing
- Table of Contents
- Clamp Bracket Components (Power Tilt)
- Clamp Bracket Components (Manual Tilt)
- Steering Arm and Copilot Components
- Driveshaft Housing Components
- Driveshaft Housing Cover Components
- Driveshaft Housing Covers
  - Removal
  - Installation
- Front Cowl
  - Removal
  - Installation
- Idle Exhaust Port Cover
  - Removal and Inspection
  - Installation
- Powerhead/Midsection Assembly Separation
- Engine Mount Replacement
  - Upper Mount
    - Removal
    - Installation
  - Lower Mount
    - Removal
    - Installation
- Clamp Brackets, Swivel Bracket - Power Tilt Models
- Clamp Brackets, Swivel Bracket - Manual Tilt Models
- Driveshaft Housing Removal
- Driveshaft Housing Installation
- Shift Operation
- Kicker Strap (Tiller Handle Model)
  - Removal
  - Installation
Section 5B - Power Tilt
- Table of Contents
- Power Tilt Specifications
- General Troubleshooting
- Power Tilt - General Information
- Power Tilt Components
- Theory of Operation
  - Power Tilt Hydraulic Diagram
  - Operation
- Power Tilt Features and Operation
- Check Fluid and Purge the Power Tilt System
  - Check Fluid
  - Purging the Power Tilt System
- Cowl-Mounted Tilt Switch
  - Removal
  - Installation
- Troubleshooting the Power Tilt System
- Power Tilt Removal
- Manual Release Valve Removal and Repair
- Power Tilt Motor
- Power Tilt Pump
  - Power Tilt Pump Disassembly
  - Power Tilt Pump Reassembly
- Power Tilt Installation
Section 6A - Gear Housing (2.15:1)
- Table of Contents
- Gearcase Specifications
- Gear Housing and Driveshaft
- Propeller Shaft
- General Service Recommendations
- Draining and Inspecting Gear Housing Lubricant
- Gear Housing Removal
- Gear Housing Disassembly
- Gear Housing Assembly
Section 7A - Throttle and Shift Linkage
- Table of Contents
- Throttle and Shift Components (Tiller Models)
- Remote Control Components
- Tiller Handle Models
- Remote Models
Section 7B - Tiller Handle
- Table of Contents
- Tiller Handle Features
- Tiller Handle Components
- Tiller Handle Yaw
- Tiller Handle Removal
- Tiller Handle Disassembly
- Throttle Cable Case
  - Disassembly/Inspection
  - Assembly
- Tiller Handle Assembly
- Tiller Handle Installation
- Shift Cable Installation
- Throttle Cable Installation
- Throttle Cable Adjustments
Section 8A - Recoil Starter
- Table of Contents
- Recoil Starter Components
- Recoil Starter Removal
- Recoil Starter Disassembly
- Recoil Starter Assembly
- Recoil Starter Installation
- Neutral Interlock Cable Adjustment
Section 9A - Color Diagrams
- Table of Contents
- 15/20 EFI FourStroke, Manual Start, Manual Tilt
- 15/20 EFI FourStroke, Electric Start, Remote Control
- 15/20 EFI FourStroke with Electric Start, Tiller Handle, and Manual Tilt
- 15/20 EFI FourStroke with Electric Start, Tiller Handle, and Power Tilt

Step Test Procedure Test Result

Step 4: Check for

battery voltage at

point 5.

Connect voltmeter red lead to point 5 and

black lead to ground.

Battery voltage measured:

•

Tilt switch is faulty.

No battery voltage measured:

• Check for loose or corroded wire at point 5.

• Open circuit in wire supplying current to point 5.

Step 5: Check for

battery voltage at

point 6.

1. Connect voltmeter red lead to point 6

and black lead to ground.

2. Press the up tilt button.

Battery voltage measured:

• Go to step 6.

No battery voltage measured:

• Relay is defective.

Step 6: Check down

relay.

Test down relay. Refer to Power Tilt

Relay Test, preceding.

Relay is good:

• Pump motor wiring is defective.

• Pump motor is defective.

Relay is faulty:

• Replace relay.

Troubleshooting the Down and Up Circuits (All Circuits Inoperative)

NOTE: Refer to the preceding wiring diagrams for test points when troubleshooting the electrical systems. Test points are

specified by number.

Step Test Procedure Test Result

Step 1: Check

fuse.

Visually inspect power tilt motor fuse.

Fuse blown:

• Correct problem that caused to blow, and

• Replace fuse.

Fuse not blown:

• Go to step 2.

Step 2: Check

battery

voltage.

Connect voltmeter red lead to point 3

and black lead to ground.

No battery voltage:

• Check battery leads for poor connections or open circuit.

• Check battery charge.

Battery voltage measured:

• Go to step 3.

Step 3: Tilt

switch.

1. Connect voltmeter red lead to point

8 and black lead to point 1.

2. Press the tilt down button.

No battery voltage:

• Go to step 4.

Battery voltage measured:

• Check black ground wires for connection or poor ground at

point 10.

• Pump motor is faulty.

Step 4: Open

circuits.

Connect voltmeter red lead to point 5

and black lead to ground.

No voltage measured:

• Go to step 5.

Battery voltage measured:

• Tilt switch is faulty or

• Open circuit in wires (green/white or blue/white) between tilt

buttons and tilt pump motor.

• Check

• Tilt switch.

• All tilt harness connections for loose or corroded connections.

• Pinched or severed wires.

Power Tilt