Mercury 20 EFI FourStroke Service Manual

Important Information
Section 1E - General
Troubleshooting
Table of Contents
Conditions Affecting Performance..................................... 1E-2
Bottom of Boat ...........................................................
1E-2
Cavitation....................................................................1E-2
Detonation.................................................................. 1E-3
Elevation, Weather, and Climate................................ 1E-3
Propeller Selection......................................................1E-3
Water Absorption........................................................ 1E-3
Weight Distribution (Passengers and Gear) Inside the
Boat.........................................................................1E-3
Compression Check...........................................................1E-4
Cylinder Leakage Test....................................................... 1E-4
Analysis...................................................................... 1E-4
Guardian Protection System.............................................. 1E-5
Warning System.................................................................1E-5
Warning Horn Location............................................... 1E-5
Warning Light Location............................................... 1E-5
Warning System Operation.........................................1E-5
Engine Overheat.........................................................1E-6
Low Oil Pressure........................................................ 1E-6
Engine Overspeed Limiter.......................................... 1E-6
Wire Color Code Abbreviations.................................. 1E-7
Warning System Wiring Diagram................................1E-7
Troubleshooting without a Computer Diagnostic System
(CDS)............................................................................. 1E-7
Troubleshooting with CDS G3........................................... 1E-7
About CDS G3............................................................ 1E-7
Connecting CDS G3................................................... 1E-8
Using CDS G3............................................................ 1E-8
Accessing ECM Information with CDS G3.........................1E-8
CDS G3 Screens (10/15/20 EFI)....................................... 1E-9
CDS G3 Live Data Screen..........................................1E-9
CDS G3 Diagnostics Screen.................................... 1E-10
Engine Control Module Pinout......................................... 1E-11
Fault Codes......................................................................1E-11
Mercury Universal Fault Codes................................ 1E-11
Mercury Universal Fault Code Table (10/15/20).......1E-12
Descriptive Fault List (10/15/20)............................... 1E-13
General Troubleshooting
90-8M0125265 eng NOVEMBER 2017 © 2018 Mercury Marine Page 1E-1
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Mercury 20 EFI FourStroke Specifications

General

Brand	Mercury
Model	20 EFI FourStroke
Category	Engine
Language	English