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20 EFI FourStroke
Mercury 20 EFI FourStroke Service Manual
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Lubricants, Sealants, Adhesives
Tube Ref No.
Description
Where Used
Part No.
95
2-4-C with PTFE
Shift shaft assembly detents and contact surfaces
92-802859A 1
Throttle and Shift Linkage
Page 7A-2
© 2018 Mercury Marine
90-8M0125265
eng
NOVEMBER 2017
344
346
Table of Contents
Important Information 1
6
Table of Contents
6
Model Specifications
7
Ignition Specifications
7
Charging and Starting Specifications
8
Fuel System Specifications
8
Cylinder Block/Crankcase Specifications
8
Piston Specifications
9
Cylinder Head Specifications
9
Oil System Specifications
10
Cooling System Specifications
11
Power Tilt Specifications
11
Gearcase Specifications
11
Important Information 1
12
Cleaning Care
13
Do Not Use Caustic Cleaning Chemicals
13
Cleaning Care for Top and Bottom Cowls
13
Inspection and Maintenance Schedule
13
Before each Use
13
After each Use
13
Every 100 Hours of Use or Once Yearly, Whichever Occurs First
13
Every 300 Hours of Use or Three Years
14
Before Periods of Storage
14
Battery Inspection
14
Flushing the Cooling System
14
Fuel System
15
Fuel System Precautions
15
Fuel Line Inspection
15
VST Vent and Cooling Hose Inspection
15
Draining Water from the Fuel Filter
15
Fuel Filter Replacement
16
Fuse Replacement - Electric Start Models
18
Spark Plug Inspection and Replacement
19
Timing Belt Inspection
19
Engine Oil
20
Changing the Oil Filter
20
Draining the Engine Oil
21
Filling the Crankcase with Oil
22
Corrosion Control Anodes
22
Propeller Replacement
24
Removal
24
Installation
25
Gearcase Lubrication
25
Draining and Inspecting Gear Housing Lubricant
25
Gearcase Lubricant Capacity
26
Gearcase Lubricant Recommendation
26
Filling the Gearcase
26
Lubrication Points
27
Storage Preparation
28
Fuel System Storage Preparation
28
Protecting External Outboard Components
29
Protecting Internal Engine Components
29
Gearcase
29
Positioning Outboard for Storage
29
Important Information 1
32
Model Year Production Code
33
Recording Serial Number
33
Engine Component Identification - Manual Start Model
34
15/20 Fourstroke EFI Manual Start Front View
34
15/20 Fourstroke EFI Manual Start Starboard View
35
15/20 Fourstroke EFI Manual Start Port View
36
15/20 Fourstroke EFI Manual Start Aft View
37
Engine Component Identification - Electric Start Model
38
15/20 Fourstroke EFI Electric Start Front View
38
15/20 Fourstroke EFI Electric Start Starboard View
39
15/20 Fourstroke EFI Electric Start Port View
40
15/20 Fourstroke EFI Electric Start Aft View
41
Following Complete Submersion
42
Engine Submerged While Running (Special Instructions)
42
Freshwater Submersion (Special Instructions)
42
Saltwater Submersion (Special Instructions)
42
Fuel Requirements
42
Low Permeation Fuel Hose Requirement
43
EPA Pressurized Portable Fuel Tank Requirements
43
Fuel Demand Valve (FDV) Requirement
43
Painting Procedures
43
Propeller Painting Procedure
43
Gearcase and Lower Housing Refinishing
44
Cowl Refinishing
44
Emissions
45
Exhaust Emission Standards
45
Emissions Information
46
Manufacturer's Certification Label
47
Service Replacement Certification Label
47
Shipping of Hazardous Material (Hazmat) and Engine/Components Containing Hazardous Material
48
Outboard Service Bulletin 2008-07
48
Overview of Regulations
48
Overview of Training Requirements
48
Shipping of Complete Engines and Major Assemblies
48
More Information on Hazardous Material
48
Important Information 1
50
Installing Outboard
51
Boat Transom Height Requirement
51
Installing Outboard on Transom
51
Lifting the Outboard
51
Start in Gear Protection
51
Steering Cable Installation
53
Steering Link Rod Fasteners
53
Remote Wiring Harness and Control Cable Installation
54
Remote Wiring Harness Connection
54
Shift Cable Installation
54
Throttle Cable Installation
55
Battery Installation
56
Mounting Battery
56
Battery Connections
57
Connecting Outboard Battery Cables
57
Disconnecting Outboard Battery Cables
57
Important Information 1
58
Conditions Affecting Performance
59
Bottom of Boat
59
Cavitation
59
Detonation
60
Elevation, Weather, and Climate
60
Propeller Selection
60
Water Absorption
60
Weight Distribution (Passengers and Gear) Inside the Boat
60
Compression Check
61
Cylinder Leakage Test
61
Analysis
61
Guardian Protection System
62
Warning System
62
Warning Horn Location
62
Warning Light Location
62
Warning System Operation
62
Engine Overheat
63
Low Oil Pressure
63
Engine Overspeed Limiter
63
Wire Color Code Abbreviations
64
Warning System Wiring Diagram
64
Troubleshooting with CDS G3
64
About CDS G3
64
Connecting CDS G3
65
Using CDS G3
65
Troubleshooting Without a Computer Diagnostic System (CDS)
64
Accessing ECM Information with CDS G3
65
CDS G3 Screens (10/15/20 EFI)
66
CDS G3 Live Data Screen
66
CDS G3 Diagnostics Screen
67
Engine Control Module Pinout
68
Fault Codes
68
Mercury Universal Fault Codes
68
Mercury Universal Fault Code Table (10/15/20)
69
Descriptive Fault List (10/15/20)
70
Electrical 2
72
Engine Control Module (ECM)
74
ECM Systems Control Matrix
75
Troubleshooting
75
Removal
75
Installation
75
General Troubleshooting
74
Ignition Theory of Operation
74
Sensors
76
Crankshaft Position Sensor
76
Wire Color Code Abbreviations
76
Engine Coolant Temperature (ECT) Sensor
78
Oil Pressure Switch
80
Temperature and Manifold Absolute Pressure (TMAP) Sensor
81
Throttle Position Sensor (TPS)
83
Flywheel
84
Ignition Components
84
Stator
85
Timing Belt
87
Ignition Coil
88
Electrical 2
92
Charging and Starting Specifications
93
General Troubleshooting
93
Starter Motor Components
95
Starter Motor and Solenoid Electrical Components
97
Charging System
99
Charging System Wiring Diagram
99
Troubleshooting the Charging System
99
Testing the Stator Charge Windings
100
Regulator/Rectifier Diode Test
100
Voltage Regulator/Rectifier Removal and Installation
101
Wire Color Code Abbreviations
99
Starter Solenoid Test
102
Starting System
102
Starting System Components
102
Starting System Description
102
Troubleshooting the Starting Circuit
102
Starting System Wiring Diagrams
103
Starter Motor
104
Starter Motor Current Draw
104
Starting System Troubleshooting Chart
104
Starter Motor Disassembly
105
Starter Motor Removal
105
Starter Motor Reassembly
106
Starter Motor Installation
109
Fuel System 3
112
Theory of Operation
113
Air Induction System
113
Fuel System
113
Fuel Pump
113
Vapor Separator Tank
113
Throttle Body
114
Engine Control Module (ECM)
114
Overview
114
ECM and Fuel Injection
114
Troubleshooting
115
Additional Information
115
Actuators
115
Function of Actuators
115
Idle Air Control (IAC)
115
Fuel Injector
116
Sensors
115
Crankshaft Position Sensor (CPS)
115
Engine Coolant Temperature (ECT) Sensor
115
Temperature and Manifold Absolute Pressure (TMAP) Sensor
115
Throttle Position Sensor (TPS)
115
Fuel System 3
118
Fuel Pressure Test
119
General Troubleshooting
119
Testing Fuel System Inlet Vacuum
119
Fuel System Wiring Diagram
120
Wire Color Code Abbreviations
120
Sensor Wiring Diagram
121
Fuel System 3
122
Fuel System Specifications
123
Fuel System Components
125
Vapor Separator Tank Components
127
Air Intake Components
129
Fuel Lift Pump
131
Fuel Lift Pump Removal
131
Fuel Lift Pump Installation
131
Vapor Separator Tank (VST)
132
VST Removal
132
VST Disassembly
134
VST Reassembly
135
Fuel Cooler
136
VST Installation
137
Camshaft Gear Cover/Vent Tank
138
Removal
138
Installation
139
Throttle Body
139
Throttle Body Removal
139
Throttle Body Installation
140
Fuel Rail
141
Fuel Rail Removal
141
Fuel Rail Disassembly
142
Fuel Rail Reassembly
142
Fuel Rail Installation
143
Air Box
144
Air Box Removal
144
Air Box Installation
144
Idle Air Control (IAC)
145
IAC Removal
145
IAC Test
145
IAC Installation
146
Powerhead
148
Cylinder Block/Crankcase Specifications
149
Piston Specifications
150
Cylinder Block and Crankcase Components
151
Crankshaft Components
153
Powerhead Removal
155
Cylinder Block Disassembly
157
Electrical Component Removal
157
Throttle Body Removal
159
Crankshaft Timing Gear Removal
159
Thermostat and Exhaust Cover Removal
160
Oil Strainer Removal
161
Crankcase and Crankshaft Removal
161
Piston Disassembly
163
Powerhead Cleaning, Inspection, and Repair
163
Flywheel
163
Crankshaft Timing Gear
164
Timing Belt
164
Anode
164
Measuring Cylinder Bore
164
Piston Measurements
164
Connecting Rod Measurements
166
Crankshaft
167
Crankcase Main Bearings
167
Connecting Rod Oil Clearance
170
Powerhead Assembly
171
Piston Assembly
171
Piston Ring Installation
171
Piston Installation
172
Crankshaft Installation
173
Crankshaft Timing Gear Installation
175
Thermostat, Exhaust Cover, and Anode Installation
175
Oil Strainer Installation
177
Throttle Body Installation
177
Electrical Component Installation
178
Powerhead Installation
180
Powerhead
186
Cylinder Head Specifications
187
Cylinder Head Components
189
Intake/Exhaust Valve Components
191
Camshaft and Oil Pump Components
193
Valve Adjustments
195
Cylinder Head Removal
196
Cylinder Head Disassembly
198
Camshaft
200
Valves
200
Valve Springs
201
Cylinder Head Resurfacing
201
Valve Guides
202
Rocker Arm and Rocker Arm Shaft Inspection
202
Valve Seat Reconditioning
202
Cleaning and Inspection
200
Cylinder Head Assembly
204
Cylinder Head Installation
206
Midsection
220
Clamp Bracket Components (Power Tilt)
223
Clamp Bracket Components (Manual Tilt)
225
Steering Arm and Copilot Components
229
Driveshaft Housing Components
231
Driveshaft Housing Cover Components
233
Driveshaft Housing Covers
235
Removal
235
Installation
236
Front Cowl
236
Removal
236
Installation
237
Idle Exhaust Port Cover
238
Removal and Inspection
238
Installation
238
Powerhead/Midsection Assembly Separation
239
Remote Control Throttle and Shift Cables
239
Removal
239
Installation
241
Engine Mount Replacement
242
Upper Mount
242
Lower Mount
242
Clamp Brackets, Swivel Bracket - Power Tilt Models
244
Clamp Brackets - Power Tilt
244
Steering Arm Removal
249
Power Tilt Removal
250
Swivel Bracket Removal
251
Swivel Bracket Inspection
251
Swivel Bracket Installation
252
Power Tilt Installation
253
Steering Arm Installation
254
Clamp Brackets, Swivel Bracket - Manual Tilt Models
256
Clamp Brackets - Manual Tilt
256
Steering Arm Removal
259
Swivel Bracket Removal
260
Swivel Bracket Inspection
260
Swivel Bracket Installation
262
Steering Arm Installation
263
Driveshaft Housing Removal
265
Driveshaft Housing Installation
266
Kicker Strap (Tiller Handle Model)
267
Removal
268
Installation
268
Shift Operation
267
Midsection
270
General Troubleshooting
271
Power Tilt - General Information
271
Power Tilt Specifications
271
Power Tilt Components
273
Theory of Operation
275
Power Tilt Hydraulic Diagram
275
Operation
275
Power Tilt Features and Operation
276
Power Tilt
276
Manual Tilt Release
276
Tilt-In Stop Adjustment
276
Check Fluid and Purge the Power Tilt System
277
Check Fluid
277
Purging the Power Tilt System
278
Cowl-Mounted Tilt Switch
278
Removal
278
Installation
278
Troubleshooting the Power Tilt System
279
Preliminary Troubleshooting Steps
279
Power Tilt Leakage Test Procedure
279
Hydraulic System Troubleshooting
280
Tilt Electrical System - General Troubleshooting
280
Power Tilt Relay Test
281
Wire Color Code Abbreviations
282
Tilt System Wiring Diagrams
282
Tilt System Troubleshooting Charts
284
Power Tilt Removal
287
Manual Release Valve Removal and Repair
288
Power Tilt Motor
289
Power Tilt Motor Removal
289
Power Tilt Motor Disassembly, Inspection, and Repair
290
Power Tilt Motor Reassembly
292
Power Tilt Pump
293
Power Tilt Pump Disassembly
293
Power Tilt Pump Reassembly
295
Power Tilt Installation
298
Lower Unit
302
Gearcase Specifications
305
Gear Housing and Driveshaft
307
Propeller Shaft
309
Draining and Inspecting Gear Housing Lubricant
311
General Service Recommendations
311
Shims
311
Seals
311
Gear Housing Removal
312
Gear Housing Disassembly
313
Bearing Carrier Disassembly
313
Propeller Shaft Disassembly
317
Water Pump, Driveshaft, and Shift Shaft Disassembly
319
Driveshaft Removal
322
Forward Gear and Reverse Gear Inspection
323
Driveshaft Pinion Bearing Removal
325
Driveshaft Inspection
326
Gear Housing Assembly
327
Pinion Bearing Installation
327
Upper Driveshaft Bearing Inspection
327
Forward Gear Bearing Installation
328
Bearing Carrier Assembly
329
Water Pump Base Assembly
331
Propeller Shaft Assembly
332
Pinion Gear and Driveshaft Installation
333
Forward Gear Backlash
334
Shift Shaft and Water Pump Base Installation
336
Water Pump Cover Assembly
338
Propeller Shaft and Bearing Carrier Installation
339
Gear Housing Installation
340
Propeller Installation
342
Attachments
344
Throttle and Shift Components (Tiller Models)
347
Remote Control Components
349
Tiller Handle Models
351
Throttle and Shift Linkage Removal
351
Shift Detent
352
Throttle and Shift Linkage Installation
352
Remote Models
353
Throttle and Shift Linkage Removal
353
Shift Detent
355
Throttle and Shift Linkage Installation
355
Attachments
358
Tiller Handle Features
359
Tiller Handle Components
361
Tiller Handle Yaw
365
Tiller Handle Disassembly
366
Tiller Handle Removal
366
Disassembly/Inspection
368
Throttle Cable Case
368
Assembly
369
Tiller Handle Assembly
370
Tiller Handle Installation
374
Shift Cable Installation
375
Throttle Cable Installation
378
Throttle Cable Adjustments
379
Recoil Starter Components
385
Recoil Starter Removal
387
Recoil Starter Disassembly
387
Recoil Starter Assembly
388
Recoil Starter Installation
392
Neutral Interlock Cable Adjustment
393
15/20 EFI Fourstroke, Manual Start, Manual Tilt
397
15/20 EFI Fourstroke, Electric Start, Remote Control
400
15/20 EFI Fourstroke with Electric Start, Tiller Handle, and Manual Tilt
401
15/20 EFI Fourstroke with Electric Start, Tiller Handle, and Power Tilt
404
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Mercury 20 EFI FourStroke Specifications
General
Brand
Mercury
Model
20 EFI FourStroke
Category
Engine
Language
English
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