Product Manual

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

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

CDS G3 Diagnostics Screen

Use the Diagnostics screen to confirm proper operation of various system components. To perform one of the listed

diagnostics, click the appropriate button, and follow the on‑screen instructions.

64646

Injector Pulse

Ignition Spark

LED Output

Horn Output

Idle Air Control

Fuel Pump Output

Cylinder Misfire

General Troubleshooting