Mercury 4.3 TKS Maintance Manual
4.3 TKS Models
(
Non-ECT
OPERATION &
MAINTENANCE
MANUAL
)
Welcome
You have selected one of the finest marine power packages available. It incorporates numerous design features to
ensure operating ease and durability.
With proper care and maintenance, you will enjoy using this product for many boating seasons. To ensure maximum
performance and carefree use, we ask that you thoroughly read this manual.
The Operation and Maintenance Manual contains specific instructions for using and maintaining your product. We
suggest that this manual remain with the product for ready reference whenever you are on the water.
Thank you for purchasing one of our products. We sincerely hope your boating will be pleasant!
Mercury Marine, Fond du Lac, Wisconsin, U.S.A.
Name / function:
John Pfeifer, President,
Mercury Marine
Read This Manual Thoroughly
IMPORTANT: If you do not understand any portion of this manual, contact your dealer. Your dealer can also provide a
demonstration of actual starting and operating procedures.
Notice
Throughout this publication, and on your power package, warnings, cautions, and notices, accompanied by the
8M0113857 1215 eng
International Hazard Symbol !, may be used to alert the installer and user to special instructions concerning a
particular service or operation that may be hazardous if performed incorrectly or carelessly. Observe them carefully.
These safety alerts alone cannot eliminate the hazards that they signal. Strict compliance with these special instructions
while performing the service, plus common sense operation, are major accident prevention measures.
WARNING
!
Indicates a hazardous situation which, if not avoided, could result in death or serious injury.
!
CAUTION
Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.
NOTICE
Indicates a situation which, if not avoided, could result in engine or major component failure.
IMPORTANT: Identifies information essential to the successful completion of the task.
NOTE: Indicates information that helps in the understanding of a particular step or action.
IMPORTANT: The operator (driver) is responsible for the correct and safe operation of the boat, the equipment aboard,
and the safety of all occupants aboard. We strongly recommend that the operator read this Operation and Maintenance
Manual and thoroughly understand the operational instructions for the power package and all related accessories before
the boat is used.
WARNING
!
The engine exhaust from this product contains chemicals known to the state of California to cause cancer, birth
defects or other reproductive harm.
4.3 TKS Models (Non-ECT)
The serial numbers are the manufacturer’s keys to numerous engineering details that apply to your Mercury Marine
power package. When contacting Mercury Marine about service, always specify model and serial numbers.
Descriptions and specifications contained herein were in effect at the time this was approved for printing. Mercury
Marine, whose policies are based on continuous improvement, reserves the right to discontinue models at any time or to
change specifications or designs without notice and without incurring obligation.
© 2016 Mercury Marine
Warranty Message
The product you have purchased comes with a limited warranty from Mercury Marine; the terms of the warranty are set forth
in the Warranty Manual included with the product. The Warranty Manual contains a description of what is covered, what is not
covered, the duration of coverage, how to best obtain warranty coverage, important disclaimers and limitations of
damages, and other related information. Please review this important information.
Copyright and Trademark Information
© MERCURY MARINE. All rights reserved. Reproduction in whole or in part without permission is prohibited.
Alpha, Axius, Bravo One, Bravo Two, Bravo Three, Circle M with Waves Logo, K‑planes, Mariner, MerCathode, MerCruiser,
Mercury, Mercury with Waves Logo, Mercury Marine, Mercury Precision Parts, Mercury Propellers, Mercury Racing,
MotorGuide, OptiMax, Quicksilver, SeaCore, Skyhook, SmartCraft, Sport‑Jet, Verado, VesselView, Zero Effort, Zeus, #1 On the
Water and We're Driven to Win are registered trademarks of Brunswick Corporation. Pro XS is a trademark of Brunswick
Corporation. Mercury Product Protection is a registered service mark of Brunswick Corporation.
Identification Records
Please record the following applicable information:
MerCruiser
Engine Model and Horsepower Engine Serial Number
Transom Assembly Serial Number (Sterndrive) Gear Ratio Sterndrive Unit Serial Number
Transmission Model (Inboard) Gear Ratio Transmission Serial Number
Propeller Number Pitch Diameter
Hull Identification Number (HIN) Purchase Date
Boat Manufacturer Boat Model Length
Exhaust Gas Emissions Certification Number (Europe Only)
TABLE OF CONTENTS
Section 1 - Getting to Know Your Power Package
Identification............................................................................... 2
Engine Serial Number Decal ............................................. 2
Alpha Sterndrive Serial Number......................................... 2
Alpha Transom Serial Number........................................... 2
Bravo Sterndrive Serial Number and Identification............. 3
Bravo Transom Serial Number........................................... 4
Lanyard Stop Switch.................................................................. 4
Keep the Lanyard Stop Switch and Lanyard Cord in Good
Operating Condition............................................................. 5
Instrumentation.......................................................................... 5
VesselView........................................................................... 5
SmartCraft Digital Instruments............................................. 6
Section 2 - On the Water
Safe Boating Recommendations............................................. 14
Carbon Monoxide Exposure.................................................... 15
Be Alert To Carbon Monoxide Poisoning........................... 15
Stay Clear of Exhaust Areas.............................................. 15
Good Ventilation ................................................................ 15
Poor Ventilation ................................................................. 16
Basic Boat Operation............................................................... 16
Launching and Boat Operation......................................... 16
Operation Chart............................................................ 16
Starting and Stopping the Engine..................................... 17
Starting the Engine....................................................... 17
Stopping the Engine..................................................... 17
Starting the Engine After It Has Been Stopped While In
Gear.................................................................................. 17
Throttle Only Operation.................................................... 17
Trailering the Boat............................................................ 18
Freezing Temperature Operation..................................... 18
Drain Plug and Bilge Pump............................................... 18
Protecting People in the Water................................................ 18
While You Are Cruising...................................................... 18
While Boat Is Stationary..................................................... 18
System Link Digital Instruments........................................... 6
Remote Controls........................................................................ 7
Panel Mount Features.......................................................... 7
Console Mount Features...................................................... 8
Power Trim................................................................................. 8
Single Engine Trim/Trailer.................................................... 9
Dual Engine Trim/Trailer...................................................... 9
Electrical System Overload Protection—Carbureted
Engines...................................................................................... 9
Audio Warning System............................................................ 12
Testing the Audio Warning System.................................... 12
High‑Speed and High‑Performance Operation........................ 18
Passenger Safety in Pontoon Boats and Deck Boats.............. 18
Boats Having an Open Front Deck.....................................18
Boats With Front‑Mounted, Raised Pedestal Fishing Seats
........................................................................................... 19
Wave and Wake Jumping........................................................ 19
Impact with Underwater Hazards............................................. 20
Drive Unit Impact Protection...............................................20
Operating with Low Water Inlets in Shallow Water.................. 21
Conditions Affecting Operation................................................ 21
Weight Distribution (Passengers and Gear) Inside the
Boat.................................................................................. 21
The Bottom of the Boat..................................................... 21
Cavitation.......................................................................... 21
Ventilation......................................................................... 21
Elevation and Climate....................................................... 22
Propeller Selection............................................................ 22
Getting Started......................................................................... 22
20‑Hour Break‑In Period................................................... 22
After Break‑In Period........................................................ 22
End of First Season Checkup........................................... 23
Section 3 - Specifications
Fuel Requirements................................................................... 26
Fuel Ratings....................................................................... 26
Using Reformulated (Oxygenated) Gasoline (USA Only)
........................................................................................... 26
Gasoline Containing Alcohol.............................................. 26
Bu16 Butanol Fuel Blends............................................ 26
Methanol and Ethanol Fuel Blends...............................26
Engine Oil................................................................................ 26
Engine Specifications............................................................... 27
4.3 TKS............................................................................. 27
Fluid Specifications.................................................................. 28
Engine................................................................................ 28
Sterndrives......................................................................... 28
Section 4 - Maintenance
Owner/Operator Responsibilities............................................. 30
Dealer Responsibilities............................................................ 30
90-8M0113857 eng DECEMBER 2015 Page i
Maintenance............................................................................ 30
Do‑It‑Yourself Maintenance Suggestions................................ 30
Inspection............................................................................... 31
Maintenance Schedule–Sterndrive Models............................ 31
Routine Maintenance...................................................... 31
Scheduled Maintenance.................................................. 31
Sealed Carburetor Mixture Screw.......................................... 32
Engine Oil............................................................................... 32
Checking........................................................................... 33
Filling................................................................................ 33
Changing Oil and Filter..................................................... 33
Easy Engine Oil Drain System.................................... 33
Engine Oil Drain Pump................................................34
Changing Filter............................................................ 34
Power Steering Fluid.............................................................. 35
Checking........................................................................... 35
Filling................................................................................ 35
Changing.......................................................................... 35
Engine Coolant....................................................................... 35
Checking........................................................................... 35
Filling................................................................................ 36
Changing ......................................................................... 37
Alpha Sterndrive Gear Lube................................................... 37
Checking........................................................................... 37
Filling................................................................................ 37
Changing.......................................................................... 38
Sterndrive Gear Lube............................................................. 39
Checking......................................................................... 39
Filling............................................................................... 39
Changing......................................................................... 39
Power Trim Fluid.................................................................... 41
Checking........................................................................... 41
Filling................................................................................ 41
Changing.......................................................................... 41
Cleaning the Flame Arrestor................................................... 42
Positive Crankcase Ventilation (PCV) Valve ................... 42
Changing..................................................................... 42
Changing the Water‑Separating Fuel Filter............................ 43
Lubrication.............................................................................. 43
Steering System.............................................................. 43
Shift Plate Control Cable Lubrication.............................. 45
Driveshaft U‑joint Splines and O‑Rings (Sterndrive Unit
Removed)........................................................................ 45
Engine Coupler................................................................ 45
Driveshaft Extension Models........................................... 46
Propellers............................................................................... 46
Propeller Repair.............................................................. 46
Alpha Propeller Removal................................................. 47
Alpha Propeller Installation.............................................. 47
Bravo One Propeller Removal......................................... 48
Bravo One Propeller Installation...................................... 48
Bravo Two Propeller Removal......................................... 49
Bravo Two Propeller Installation...................................... 49
Bravo Three Propeller Removal...................................... 50
Bravo Three Propeller Installation................................... 51
Serpentine Drive Belt.............................................................. 52
Checking........................................................................... 52
Replacing Belt and/or Adjusting Tension.......................... 53
Flushing the Power Package (Alpha)..................................... 53
Flushing Attachments....................................................... 54
Sterndrive Water Pickups................................................. 54
Flushing the Power Package (Bravo)..................................... 55
General Information......................................................... 55
Flushing the Power Package........................................... 55
Flushing Attachments..................................................55
Sterndrive Water Pickups............................................56
Alternative Water Pickups........................................... 57
SeaCore Power Package Flushing Procedure................ 58
Models Using The Sterndrive Water Pickup............... 58
Battery.................................................................................... 61
Corrosion Protection............................................................... 61
Corrosion Information...................................................... 61
Maintaining Ground Circuit Continuity............................. 61
Sterndrive Corrosion Protection Components................. 62
MerCathode System Battery Requirements.................... 64
MerCathode Theory of Operation.................................... 64
Power Package Exterior Surfaces................................... 65
Boat Bottom Care............................................................ 65
Painting Your Power Package......................................... 65
Sterndrive Surface Care.................................................. 66
Section 5 - Storage
Cold Weather or Extended Storage........................................ 70
Reformulated (Oxygenated) Gasolines (U.S.A. Only)..... 70
Fuel Containing Alcohol.................................................. 70
Preparing Power Package for Storage—Carburetor
Models............................................................................. 71
Engine and Fuel System Preparation......................... 71
Draining the Seawater System............................................... 72
Drain System Identification.............................................. 72
Air Actuated Single‑Point Drain System......................72
Manual Single‑Point Drain System, Seawater cooled
models ........................................................................73
4.3 ECT Single‑Point Drain System with Plug............ 73
Three‑Point Manual Drain System, Seawater
cooled..........................................................................73
Multipoint Drain (MPD) System................................... 74
Air Actuated Single‑Point Drain System.......................... 74
Boat in the Water........................................................ 74
Boat Out of the Water................................................. 76
Manual Single‑Point Drain System (Alpha)..................... 78
Boat in the Water........................................................ 78
Boat Out of the Water................................................. 79
Three‑Point Manual Drain System—Seawater Cooled... 81
Boat in the Water........................................................ 81
Boat Out of the Water................................................. 81
Draining Water from the Gen III Cool Fuel Module......... 82
Draining the Sterndrive........................................................... 82
Battery Storage....................................................................... 83
Recommissioning the Power Package................................... 83
Section 6 - Troubleshooting
Starter Motor Will Not Crank Engine, or Cranks Slow............ 86
Engine Will Not Start or Is Hard to Start................................. 86
Page ii 90-8M0113857 eng DECEMBER 2015
Engine Runs Rough, Misses, or Backfires............................. 86
Poor Performance.................................................................. 86
Excessive Engine Temperature............................................... 87
Insufficient Engine Temperature.............................................. 87
Low Engine Oil Pressure......................................................... 87
Battery Will Not Recharge........................................................ 87
Remote Control Is Difficult to Move, Has Excessive Play, or
Makes Unusual Sounds........................................................... 87
Section 7 - Customer Assistance Information
Steering Wheel Jerks or Is Difficult to Turn.............................. 88
Power Trim Does Not Operate (Motor Does Not Operate)...... 88
Power Trim Does Not Operate (Motor Operates but Sterndrive
Unit Does Not Move)................................................................ 88
Owner Service Assistance....................................................... 90
Local Repair Service.......................................................... 90
Service Away From Home..................................................90
Stolen Power Package....................................................... 90
Attention Required After Submersion................................. 90
Replacement Service Parts................................................ 90
Parts and Accessories Inquiries................................... 90
Resolving a Problem.......................................................... 90
Contact Information for Mercury Marine Customer Service
........................................................................................... 91
Customer Service Literature.................................................... 91
English Language.............................................................. 91
Other Languages................................................................92
Ordering Literature................................................................... 92
United States and Canada................................................. 92
Outside the United States and Canada.............................. 92
Section 8 - Checklists
Predelivery Inspection (PDI).................................................... 94 Customer Delivery Inspection (CDI)........................................ 95
Section 9 - Maintenance Log
Scheduled Maintenance Log................................................... 98 Vessel Maintenance Notes...................................................... 99
90-8M0113857 eng DECEMBER 2015 Page iii
Page iv 90-8M0113857 eng DECEMBER 2015
Section 1 - Getting to Know Your Power Package
Section 1 - Getting to Know Your Power Package
Table of Contents
Identification........................................................................... 2
Engine Serial Number Decal .......................................... 2
Alpha Sterndrive Serial Number...................................... 2
Alpha Transom Serial Number........................................ 2
Bravo Sterndrive Serial Number and Identification.......... 3
Bravo Transom Serial Number........................................ 4
Lanyard Stop Switch............................................................... 4
Keep the Lanyard Stop Switch and Lanyard Cord in
Good Operating Condition .............................................. 5
Instrumentation....................................................................... 5
VesselView ..................................................................... 5
SmartCraft Digital Instruments ....................................... 6
1
System Link Digital Instruments ..................................... 6
Remote Controls..................................................................... 7
Panel Mount Features .................................................... 7
Console Mount Features ................................................ 8
Power Trim............................................................................. 8
Single Engine Trim/Trailer .............................................. 9
Dual Engine Trim/Trailer ................................................. 9
Electrical System Overload Protection—Carbureted Engines
................................................................................................ 9
Audio Warning System......................................................... 12
Testing the Audio Warning System .............................. 12
90-8M0113857 eng DECEMBER 2015 Page 1
Section 1 - Getting to Know Your Power Package
26301
54406
Transom Serial No.
53651
Identification
The serial numbers are the manufacturer's keys to numerous engineering details which apply to your MerCruiser power
package. When contacting MerCruiser about service, always specify model and serial numbers.
Engine Serial Number Decal
The serial number decal is located on the engine cover.
Serial numbers and maintenance color codes decal
The engine serial number is also stamped in the engine block.
Alpha Sterndrive Serial Number
The drive serial number and the drive ratio are located on the port side of the sterndrive.
Alpha sterndrive
Alpha Transom Serial Number
The Alpha transom serial number is stamped in the transom assembly decal.
Page 2 90-8M0113857 eng DECEMBER 2015
Section 1 - Getting to Know Your Power Package
44425
33533
33534
The serial number is also stamped on the gimbal housing. This is used as a permanent reference for authorized MerCruiser
dealers.
Serial number location on gimbal housing
Bravo Sterndrive Serial Number and Identification
The Bravo sterndrive serial number, gear ratio, model number, and bar code are embedded in the ground plate on the port side
of the sterndrive.
Bravo sterndrive information on ground plate
The serial number is also stamped as a permanent reference on the sterndrive casting inside the back cover.
Bravo sterndrive serial number stamping
90-8M0113857 eng DECEMBER 2015 Page 3
Section 1 - Getting to Know Your Power Package
25904
a
25905
a
c
a
b
53910
OFF
RUN
ATTACH LANYARD
Bravo Transom Serial Number
The Bravo transom serial number is stamped in the U‑bolt plate of the Bravo transom assembly.
Bravo transom assembly U-bolt plate
a - Transom assembly serial number
The serial number is also stamped on the gimbal housing. This is used as a permanent reference for authorized MerCruiser
dealers.
Gimbal housing with serial
number stamping
a - Transom assembly serial
number
Lanyard Stop Switch
A lanyard switch is designed to shut down the engine in the event the operator unexpectedly moves away from the helm, as
may happen in an accidental ejection. The lanyard is connected to the operator's personal flotation device or wrist.
A decal near the lanyard stop switch reminds the operator to attach the lanyard to his or her personal flotation device or wrist.
a - Lanyard cord clip
b - Lanyard decal
c - Lanyard stop switch
Accidental ejections, such as falling overboard, are more likely to occur in:
• Low‑sided sport boats
• Bass boats
Page 4 90-8M0113857 eng DECEMBER 2015
Section 1 - Getting to Know Your Power Package
• High‑performance boats
Accidental ejections can also occur from:
• Poor operating practices
• Sitting on the seat or gunwale at planing speeds
• Standing at planing speeds
• Operating at planing speeds in shallow or obstacle‑infested waters
• Releasing your grip on the steering wheel
• Carelessness caused by consuming alcohol or drugs
• High‑speed boating maneuvers
The lanyard is a cord usually between 122 and 152 cm (4 and 5 ft) long when stretched out, with an element on one end made
to be inserted into the switch, and a snap on the other end for attaching to the operator. The lanyard is coiled to make its at‑rest
condition as short as possible to minimize the likelihood of lanyard entanglement with nearby objects. Its stretched‑out length is
made to minimize the likelihood of accidental activation should the operator choose to move around in an area close to the
operator's normal position. The operator can shorten the lanyard by wrapping the lanyard around his wrist, or by tying a knot in
the lanyard.
Activation of the lanyard stop switch will stop the engine immediately, but the boat will continue to coast for some distance,
depending upon its velocity. While the boat is coasting, it can cause injury to anyone in the boat's path as it would under power.
Instruct all passengers on the proper starting and operating procedures should they be required to operate the boat in an
emergency.
WARNING
!
If the operator falls out of the boat, stop the engine immediately to reduce the possibility of serious injury or death from being
struck by the boat. Always properly connect the operator to the stop switch using a lanyard.
Accidental or unintended activation of the switch during normal operation is also a possibility. This could cause any, or all, of
the following potentially hazardous situations:
• Occupants could be thrown forward due to unexpected loss of forward motion, a particular concern for passengers in the
front of the boat who could be ejected over the bow and possibly struck by the propulsion or steering components.
• Loss of power and directional control in heavy seas, strong current, or high winds.
• Loss of control when docking.
WARNING
!
Avoid serious injury or death from deceleration forces resulting from accidental or unintended stop switch activation. The boat
operator should never leave the operator's station without first disconnecting the stop switch lanyard from the operator.
Keep the Lanyard Stop Switch and Lanyard Cord in Good Operating Condition
Before each use, ensure that the lanyard stop switch works properly. Start the engine, and then stop it by pulling the lanyard
cord. If the engine does not stop, have the switch repaired before operating the boat.
Before each use, inspect the lanyard cord to ensure that it is in good working condition and that there are no breaks, cuts, or
wear to the cord. Check that the clips on the ends of the cord are in good condition. Replace any damaged or worn lanyard
cords.
Instrumentation
VesselView
There are several VesselView products available. VesselView will display all engine information, fault codes, vessel
information, basic navigation data, and system information. When an operating system error or failure occurs, VesselView
displays an alarm message.
VesselView may also be connected to other vessel systems such as GPS, generators, and chartplotters. This vessel
integration allows the operator to monitor and control a wide range of vessel systems from a single display.
90-8M0113857 eng DECEMBER 2015 Page 5
Section 1 - Getting to Know Your Power Package
56038
a
b
c
c
50400
Refer to the VesselView operator's manual for more information.
VesselView 7
SmartCraft Digital Instruments
The SmartCraft instrument package augments the VesselView display. The instrument package may include:
• Tachometer
• Speedometer
• Engine coolant temperature
• Engine oil pressure
• Battery voltage
• Fuel consumption
• Engine operating hours
SmartCraft tachometer and speedometer
a - Tachometer
b - Speedometer
c - LCD display
The SmartCraft instrument package also aids in identifying fault codes associated with the engine audio warning system. The
SmartCraft instrument package displays critical engine alarm data and other potential problems on its LCD display.
For basic operation information on the SmartCraft instrument package and for details on the warning functions monitored by the
system, refer to the manual provided with your gauge package.
System Link Digital Instruments
Some instrumentation packages include system link gauges that augment the information provided by VesselView or a
SmartCraft system tachometer and speedometer. The owner and operator should be familiar with all the instruments and their
functions on the boat. Have your boat dealer explain the gauges and normal readings that appear on your boat.
Page 6 90-8M0113857 eng DECEMBER 2015
Section 1 - Getting to Know Your Power Package
abc
d
37925
The following digital instruments may be included with your power package.
System Link digital gauges
Item Gauge Indicates
a Oil pressure gauge Engine oil pressure
b Voltmeter Battery voltage
c Water temperature gauge Engine operating temperature
d Fuel gauge Quantity of fuel in tank
Remote Controls
Your boat may be equipped with Mercury Precision Parts or Quicksilver remote controls. All controls may not have all features
shown. Consult your dealer for a description and/or demonstration of your remote control.
Panel Mount Features
a
f
b
e
a - Neutral lock button
b - Throttle only button
c - Lanyard stop switch
d - Control handle tension adjustment screw
e - Control handle
f - Trim/tilt button
c
d
mc77019-1
Neutral lock button ‑ Prevents accidental shift and throttle engagement. Neutral lock button must be pushed into move the
control handle out of neutral.
Throttle only button ‑ Allows engine throttle advancement without shifting the engine. This is done by disengaging the shift
mechanism from the control handle. The throttle only button can be depressed only when the remote control handle is in the
neutral position, and should only be used to assist in starting the engine.
Lanyard stop switch ‑ Turns the ignition off whenever the operator (when attached to the lanyard) moves far enough away
from the operator's position to activate the switch. Refer to Lanyard Stop Switch for information on the use of this switch.
Control handle ‑ Operation of the shift and throttle are controlled by the movement of the control handle. Push the control
handle forward from neutral with a quick firm motion to the first detent for forward gear. Continue pushing forward to increase
speed. Pull the control handle back from neutral with a quick firm motion to the first detent for reverse gear and continue
pushing back to increase speed.
Control handle tension adjustment screw (not visible) ‑ This screw is used to adjust the effort required to move the remote
control handle. Refer to instructions provided with remote control for complete adjustment instructions.
Trim/tilt button ‑ Refer to Power Trim.
90-8M0113857 eng DECEMBER 2015 Page 7
Section 1 - Getting to Know Your Power Package
Console Mount Features
b
b
c
d
a
a
Throttle only button ‑ Allows engine throttle advancement without shifting the engine. This is done by disengaging the shift
mechanism from the control handle. The throttle only button can be depressed only when the remote control handle is in the
neutral position.
Control handles ‑ Operation of the shift and throttle are controlled by the movement of the control handle. Push the control
handle forward from neutral with a quick firm motion to the first detent for forward gear and continue pushing forward to
increase speed. Pull the control handle back from neutral with a quick firm motion to the first detent for reverse gear and
continue pushing back to increase speed.
Control handle tension adjustment screw (not visible) ‑ This screw is used to adjust the effort required to move the remote
control handle. Refer to instructions provided with remote control for complete adjustment instructions.
Power trim switch ‑ See Power Trim section for detailed power trim operating procedures.
Trailer switch ‑ Used to raise drive unit for trailering, launching, beaching or shallow water operation. See Power Trim for
detailed trailer switch operation.
c
d
mc79503-1
a - Throttle only button
b - Control handle
c - Power trim switch
d - Trailer switch
Power Trim
Power trim allows the operator to adjust the sterndrive angle while underway, to provide the ideal boat angle for varying load
and water conditions. Also, the trailering feature allows the operator to raise and lower the sterndrive unit for trailering,
beaching, launching, low speed (below 1200 RPM engine speed), and shallow water operation.
WARNING
!
Excessive trim can cause serious injury or death at high speeds. Use caution when trimming the sterndrive, and never trim
out beyond the gimbal ring support flanges while the boat is underway or at engine speeds above 1200 RPM.
For best performance trim the sterndrive unit so that the boat bottom is at a 3–5° angle to the water.
3 - 5
mc79528
Trimming sterndrive unit up/out can:
• Generally increase top speed
• Increase clearance over submerged objects or a shallow bottom
• Cause boat to accelerate and plane off slower
• In excess, cause boat porpoising (bouncing) or propeller ventilation
Page 8 90-8M0113857 eng DECEMBER 2015
Section 1 - Getting to Know Your Power Package
• Cause engine overheating if trimmed up/out to a point where any cooling water intake holes are above the waterline
mc78529
Trimming sterndrive unit down/in can:
• Help the boat accelerate and plane off quicker
• Generally improve the ride in choppy water
• In most cases, reduce boat speed
• If in excess, lower the bow of some boats to a point at which they begin to plow with their bow in the water while on plane.
This can result in an unexpected turn in either direction called bow steering or over steering if any turn is attempted or if a
significant wave is encountered.
mc79530
Single Engine Trim/Trailer
Single engine applications will have a button that can be pressed to trim the sterndrive unit up or down.
To raise the sterndrive unit for trailering, beaching, launching, low speed (below 1200 RPM), and shallow water operation push
the trim button to raise the sterndrive unit to the full up/out position.
Some controls also have a trailer button that trims the sterndrive to a position suitable for trailer purposes only.
Dual Engine Trim/Trailer
NOTICE
If using external tie bars, raising or lowering the drives independently of each other can damage the drive and steering
systems. If using an external tie bar, raise and lower all drives together as a unit.
Dual engine applications may have a single integral button to operate both sterndrive units simultaneously or may have
separate buttons for each sterndrive unit.
Some controls also have a trailer button that trims the sterndrives to a position suitable for trailer purposes only.
Electrical System Overload Protection—Carbureted Engines
If an electrical overload occurs, a fuse will blow or the circuit breaker will open. The cause must be found and corrected before
replacing the fuse or resetting the circuit breaker.
NOTE: In an emergency, when the engine must be operated and the cause for the high current draw cannot be located and
corrected, turn off or disconnect all accessories connected to the engine and instrumentation wiring. Reset the circuit breaker. If
the breaker remains open, the electrical overload has not been eliminated. Further checks must be made on the electrical
system. Contact your authorized dealer as soon as possible.
90-8M0113857 eng DECEMBER 2015 Page 9
Section 1 - Getting to Know Your Power Package
51185
1. A circuit breaker protects the engine wiring harness and the instrumentation power lead. Reset the breaker by pushing the
red button.
Engine wiring harness and instrumentation circuit breaker
2. A 20‑amp fuse is located near the carburetor body. This fuse protects the fuel pump and ignition system circuits.
7524
3. A 90‑amp fuse, located on the large post of the starter solenoid, protects the engine wiring harness if an electrical overload
occurs.
mc74907-1
Page 10 90-8M0113857 eng DECEMBER 2015
Section 1 - Getting to Know Your Power Package
4. A 15‑amp accessory fuse is located on the rear of the engine. This fuse protects the accessory circuits.
7524
5. A 20‑amp fuse may be located in the ignition switch "I" terminal lead to protect the electrical system. Check for an open
fuse or an open circuit breaker if the ignition key is turned to the "START" position and nothing happens.
mc70525-1
6. The power trim system is protected from overload by a 110‑amp fuse and a 20‑amp spade fuse on the power trim pump.
The trim pump may also have an in‑line circuit protection device in the power trim positive lead near the battery switch or
battery connection.
a - 20‑amp spade fuse
b - 110‑amp fuse
a
b
9208
90-8M0113857 eng DECEMBER 2015 Page 11
Section 1 - Getting to Know Your Power Package
a
c
50534
b
7. The Quicksilver MerCathode system has a 20‑amp fuse which connects to the positive (+) terminal on the controller. If the
fuse is open, the system will not operate resulting in a loss of corrosion protection.
a - MerCathode
b - Red/purple wire
c - 20‑amp fuse
Audio Warning System
The Mercury MerCruiser power package may be equipped with an audio warning system. The audio warning system will not
protect the engine from damage. It is designed to warn the operator that a problem has occurred.
The audio warning system will sound with a continuous horn if one of the following occurs:
• Engine oil pressure too low
• Engine temperature too hot
• Sterndrive oil level too low (if equipped with a drive reservoir having low oil level switch)
• Transmission temperature is too hot (if equipped)
NOTICE
A continuous horn indicates a critical fault. Operating the engine during a critical fault can damage components. If the
warning horn emits a continuous beep, do not operate the engine unless avoiding a hazardous situation.
If the alarm sounds, stop the engine immediately. Investigate cause and correct it, if possible. If the cause cannot be
determined, contact your authorized Mercury MerCruiser dealer.
Testing the Audio Warning System
1. Turn the ignition switch to the "ON" position without cranking the engine.
2. Listen for the audio alarm. The alarm will sound if the system is functioning correctly.
Page 12 90-8M0113857 eng DECEMBER 2015
Table of Contents
Section 2 - On the Water
Section 2 - On the Water
Safe Boating Recommendations.......................................... 14
Carbon Monoxide Exposure................................................. 15
Be Alert To Carbon Monoxide Poisoning ..................... 15
Stay Clear of Exhaust Areas ........................................ 15
Good Ventilation .......................................................... 15
Poor Ventilation ........................................................... 16
Basic Boat Operation............................................................ 16
Launching and Boat Operation...................................... 16
Operation Chart ..................................................... 16
Starting and Stopping the Engine.................................. 17
Starting the Engine ................................................ 17
Stopping the Engine .............................................. 17
Starting the Engine After It Has Been Stopped While In
Gear............................................................................... 17
Throttle Only Operation................................................. 17
Trailering the Boat......................................................... 18
Freezing Temperature Operation.................................. 18
Drain Plug and Bilge Pump............................................18
Protecting People in the Water............................................. 18
While You Are Cruising ................................................ 18
While Boat Is Stationary ............................................... 18
High‑Speed and High‑Performance Operation..................... 18
Passenger Safety in Pontoon Boats and Deck Boats.......... 18
Boats Having an Open Front Deck ............................... 18
Boats With Front‑Mounted, Raised Pedestal Fishing
Seats ............................................................................ 19
Wave and Wake Jumping..................................................... 19
Impact with Underwater Hazards......................................... 20
Drive Unit Impact Protection ......................................... 20
Operating with Low Water Inlets in Shallow Water............... 21
Conditions Affecting Operation............................................. 21
Weight Distribution (Passengers and Gear) Inside the
Boat............................................................................... 21
The Bottom of the Boat.................................................. 21
Cavitation....................................................................... 21
Ventilation...................................................................... 21
Elevation and Climate.................................................... 22
Propeller Selection.........................................................22
Getting Started..................................................................... 22
20‑Hour Break‑In Period................................................ 22
After Break‑In Period..................................................... 22
End of First Season Checkup........................................ 23
2
90-8M0113857 eng DECEMBER 2015 Page 13
Section 2 - On the Water
Safe Boating Recommendations
To safely enjoy the waterways, familiarize yourself with local and all other governmental boating regulations and restrictions
and consider the following suggestions.
Know and obey all nautical rules and laws of the waterways.
• We recommend that all powerboat operators complete a boating safety course. In the U.S., the U.S. Coast Guard Auxiliary,
the Power Squadron, the Red Cross, and your state or provincial boating law enforcement agency provide courses. For
more information in the U.S., call the Boat U.S. Foundation at 1‑800‑336‑BOAT (2628).
Perform safety checks and required maintenance.
• Follow a regular schedule and ensure that all repairs are properly made.
Check safety equipment onboard.
• Here are some suggestions of the types of safety equipment to carry when boating:
Approved fire extinguishers
Signal devices: flashlight, rockets or flares, flag, and whistle or horn
Tools necessary for minor repairs
Anchor and extra anchor line
Manual bilge pump and extra drain plugs
Drinking water
Radio
Paddle or oar
Spare propeller, thrust hubs, and an appropriate wrench
First aid kit and instructions
Waterproof storage containers
Spare operating equipment, batteries, bulbs, and fuses
Compass and map or chart of the area
Personal flotation device (one per person onboard)
Watch for signs of weather change and avoid foul weather and rough‑sea boating.
Tell someone where you are going and when you expect to return.
Passenger boarding.
• Stop the engine whenever passengers are boarding, unloading, or are near the back (stern) of the boat. Shifting the drive
unit into neutral is not sufficient.
Use personal flotation devices.
• Federal law requires that there be a U.S. Coast Guard‑approved life jacket (personal flotation device), correctly sized and
readily accessible for every person onboard, plus a throwable cushion or ring. We strongly advise that everyone wear a life
jacket at all times while in the boat.
Prepare other boat operators.
• Instruct at least one person onboard in the basics of starting and operating the engine and boat handling in case the driver
becomes disabled or falls overboard.
Do not overload your boat.
• Most boats are rated and certified for maximum load (weight) capacities (refer to your boat's capacity plate). Know your
boat's operating and loading limitations. Know if your boat will float if it is full of water. When in doubt, contact your
authorized Mercury Marine dealer or the boat manufacturer.
Ensure that everyone in the boat is properly seated.
• Do not allow anyone to sit or ride on any part of the boat that was not intended for such use. This includes the backs of
seats, gunwales, transom, bow, decks, raised fishing seats, and any rotating fishing seat. Passengers should not sit or ride
anywhere that sudden unexpected acceleration, sudden stopping, unexpected loss of boat control, or sudden boat
movement could cause a person to be thrown overboard or into the boat. Ensure that all passengers have a proper seat
and are in it before any boat movement.
Never operate a boat while under the influence of alcohol or drugs. It is the law.
• Alcohol or drugs can impair your judgment and greatly reduce your ability to react quickly.
Know your boating area and avoid hazardous locations.
Page 14 90-8M0113857 eng DECEMBER 2015
Section 2 - On the Water
43367
Be alert.
• The operator of the boat is responsible by law to maintain a proper lookout by sight and hearing. The operator must have
an unobstructed view particularly to the front. No passengers, load, or fishing seats should block the operator's view when
the boat is above idle or planing transition speed. Watch out for others, the water, and your wake.
Never drive your boat directly behind a water skier.
• Your boat traveling at 40 km/h (25 mph) will overtake a fallen skier who is 61 m (200 ft) in front of you in five seconds.
Watch fallen skiers.
• When using your boat for waterskiing or similar activities, always keep a fallen or down skier on the operator's side of the
boat while returning to attend to the skier. The operator should always have the down skier in sight and never back up to
the skier or anyone in the water.
Report accidents.
• Boat operators are required by law to file a boating accident report with their state boating law enforcement agency when
their boat is involved in certain boating accidents. A boating accident must be reported if 1) there is loss of life or probable
loss of life, 2) there is personal injury requiring medical treatment beyond first aid, 3) there is damage to boats or other
property where the damage value exceeds $500.00, or 4) there is complete loss of the boat. Seek further assistance from
local law enforcement.
Carbon Monoxide Exposure
Be Alert To Carbon Monoxide Poisoning
Carbon monoxide (CO) is a deadly gas that is present in the exhaust fumes of all internal combustion engines, including the
engines that propel boats, and the generators that power boat accessories. By itself, CO is odorless, colorless, and tasteless,
but if you can smell or taste engine exhaust, you are inhaling CO.
Early symptoms of carbon monoxide poisoning, which are similar to the symptoms of seasickness and intoxication, include
headache, dizziness, drowsiness, and nausea.
WARNING
!
Inhaling engine exhaust gases can result in carbon monoxide poisoning, which can lead to unconsciousness, brain damage,
or death. Avoid exposure to carbon monoxide.
Stay clear from exhaust areas when engine is running. Keep the boat well‑ventilated while at rest or underway.
Stay Clear of Exhaust Areas
Engine exhaust gases contain harmful carbon monoxide. Avoid areas of concentrated engine exhaust gases. When engines
are running, keep swimmers away from the boat, and do not sit, lie, or stand on swim platforms or boarding ladders. While
underway, do not allow passengers to be positioned immediately behind the boat (platform dragging, teak/body surfing). This
dangerous practice not only places a person in an area of high engine exhaust concentration, but also subjects them to the
possibility of injury from the boat propeller.
Good Ventilation
Ventilate the passenger area, open side curtains or forward hatches to remove fumes.
Example of desired air flow through the boat:
90-8M0113857 eng DECEMBER 2015 Page 15
Section 2 - On the Water
21626
a
b
a
b
43368
Poor Ventilation
Under certain running or wind conditions, permanently enclosed or canvas enclosed cabins or cockpits with insufficient
ventilation may draw in carbon monoxide. Install one or more carbon monoxide detectors in your boat.
Although the occurrence is rare, on a very calm day, swimmers and passengers in an open area of a stationary boat that
contains or is near a running engine may be exposed to a hazardous level of carbon monoxide.
1. Examples of poor ventilation while the boat is stationary:
a - Operating the engine when the boat
is moored in a confined space
b - Mooring close to another boat that
has its engine operating
2. Examples of poor ventilation while the boat is moving:
a - Operating the boat with the
trim angle of the bow too
high
b - Operating the boat with no
forward hatches open
(station wagon effect)
Basic Boat Operation
Launching and Boat Operation
IMPORTANT: Install bilge drain plug prior to launching boat.
Operation Chart
Operation Chart
BEFORE STARTING AFTER STARTING WHILE UNDERWAY AFTER STOPPING
Observe all gauges to
Install bilge drain plug.
Open engine hatch.
Turn battery switch on.
Operate bilge blowers. Check steering operation.
Open fuel shut off valve.
Open seacock, if equipped. Drain bilge.
Close the drain system.
Place sterndrive unit in full down/in
position.
Check the engine oil.
Perform all other checks specified by your
dealer and/or boatbuilder.
Listen for the audio warning alarm to sound
when the ignition switch is in the "ON"
position.
check condition of engine.
If not normal, stop engine.
Check for fuel, oil, water,
fluid, and exhaust leaks.
Check shift and throttle
control operation.
Observe all gauges to
check condition of
engine. If not normal,
stop engine.
Listen for the audio
alarm.
Turn ignition key to the
"OFF" position.
Turn battery switch to the
"OFF" position.
Close fuel shut off valve.
Close seacock, if
equipped.
Flush cooling system if in
saltwater.
Page 16 90-8M0113857 eng DECEMBER 2015
Section 2 - On the Water
Starting and Stopping the Engine
NOTE: Only perform those functions applicable to your power package.
Starting the Engine
1.
Check all items listed in the Operation Chart.
2. Place the remote control handle in neutral.
NOTICE
Without sufficient cooling water, the engine, the water pump, and other components will overheat and suffer damage. Provide
a sufficient supply of water to the water inlets during operation.
WARNING
!
Explosive fumes contained in the engine compartment can cause serious injury or death from fire or explosion. Before
starting the engine, operate the bilge blower or vent the engine compartment for at least five minutes.
3. Turn ignition key to "START." Release key when engine starts and allow switch to return to the "ON" position. Allow engine
to warm up (6–10 minutes on first start of the day).
NOTE: If the engine has not run for a long period of time it may require a couple of attempts while the fuel bowl refills.
4. If engine does not start after three attempts:
a. Push the throttle only button and position the remote control handle/throttle lever to the 1/4 throttle position.
b. Turn ignition key to "START." Release key when engine starts and allow switch to return to the "ON" position.
5. If engine does not start after step 4:
a. Move the remote control handle/throttle lever to full throttle position, then return to 1/4 throttle.
b. Turn ignition key to "START." Release key when engine starts and allow switch to return to the "ON" position.
6. Inspect the power package for fuel, oil, water, and exhaust leaks.
7. Move control handle with a firm, quick motion forward to shift to forward gear, or backward to shift to reverse. After shifting,
advance throttle to desired setting.
NOTICE
Shifting into gear at engine speeds above idle will damage the gearcase. Shifting into gear when the engine is not running
can misalign the clutch, preventing proper shifting. Always shift the gearcase into gear when the engine is operating at idle. If
you must shift while the engine is not operating, rotate the propeller shaft in the appropriate direction during shifting.
Stopping the Engine
1. Move the remote control handle to neutral/idle and allow the engine to slow to idle speed. If engine has been operated at
high speed for a long period of time, allow the engine to cool at idle speed for 3–5 minutes.
2. Turn ignition key to the "OFF" position.
Starting the Engine After It Has Been Stopped While In Gear
IMPORTANT: Avoid stopping the engine if the sterndrive unit is in gear. If the engine does stop, refer to the following
procedure:
1. Push and pull repeatedly on the remote control handle until handle returns to the neutral/idle position. This may take
several tries if the power package was operating above idle RPM when the engine stopped.
2. After the handle returns to the neutral/idle position, resume normal starting procedures.
Throttle Only Operation
1.
Refer to Remote Controls section for remote control features.
2. Move the control lever to the idle/neutral position.
3. Depress and hold the throttle only button, and move the control lever to the idle/forward or idle/reverse position.
4. Advancing the control lever beyond the idle/forward or idle/reverse position will cause engine speed to increase.
IMPORTANT: Moving the control lever back to the idle/neutral position will disengage the throttle only button and allow the
engine to shift into gear.
5. Throttle only mode is deactivated by moving the control lever to the idle/neutral position. Moving the control lever from the
idle/neutral position to the idle/forward or idle/reverse position without pressing the throttle only button will shift the unit into
the chosen gear.
90-8M0113857 eng DECEMBER 2015 Page 17
Section 2 - On the Water
21604
Trailering the Boat
Your boat can be trailered with the sterndrive unit in the up or down position. Adequate clearance is required between the road
and sterndrive when transporting.
If adequate road clearance is a problem, place the sterndrive unit in full trailer position and support it with an optional trailer kit
which is available from your authorized Mercury MerCruiser dealer.
Freezing Temperature Operation
IMPORTANT: If the boat is operated during periods of freezing temperature, precautions must be taken to prevent freeze
damage to the power package. Damage caused by freezing is not covered by Mercury MerCruiser Limited Warranty.
Drain Plug and Bilge Pump
The engine compartment in your boat is a natural place for water to collect. For this reason, boats are normally equipped with a
drain plug and/or a bilge pump. It is very important to check these items on a regular basis to ensure that the water level does
not come into contact with your power package. Components on your engine will be damaged if submerged. Damage caused
by submersion is not covered by the Mercury MerCruiser Limited Warranty.
Protecting People in the Water
While You Are Cruising
It is very difficult for a person in the water to take quick action to avoid a boat heading in their direction, even at slow speeds.
Always slow down and exercise extreme caution any time you are boating in an area where there might be people in the water.
Whenever a boat is moving (even coasting) and the gear shift is in neutral, there is sufficient force by the water on the propeller
to cause the propeller to rotate. This neutral propeller rotation can cause serious injury.
While Boat Is Stationary
WARNING
!
A spinning propeller, a moving boat, or any solid device attached to the boat can cause serious injury or death to swimmers.
Stop the engine immediately whenever anyone in the water is near your boat.
Shift into neutral and shut off the engine before allowing people to swim or be in the water near your boat.
High‑Speed and High‑Performance Operation
If your boat is considered a high‑speed or high‑performance boat and you are unfamiliar with its operation, we recommend that
you never operate it at its high speed capability without first requesting an initial orientation and demonstration ride with your
dealer or an operator experienced with your boat. For additional information, refer to Hi‑Performance Boat Operation booklet
(90‑849250R03) from your dealer, distributor, or Mercury Marine.
Passenger Safety in Pontoon Boats and Deck Boats
Whenever the boat is in motion, observe the location of all passengers. Do not allow any passengers to stand or use seats
other than those designated for traveling faster than idle speed. A sudden reduction in boat speed, such as plunging into a
large wave or wake, a sudden throttle reduction, or a sharp change of boat direction, could throw them over the front of the
boat. Falling over the front of the boat between the two pontoons will position them to be run over.
Boats Having an Open Front Deck
No one should ever be on the deck in front of the fence while the boat is in motion. Keep all passengers behind the front fence
or enclosure.
Page 18 90-8M0113857 eng DECEMBER 2015
Section 2 - On the Water
Persons on the front deck could easily be thrown overboard or persons dangling their feet over the front edge could get their
legs caught by a wave and pulled into the water.
mc79555-1
WARNING
!
Sitting or standing in an area of the boat not designed for passengers at speeds above idle can cause serious injury or death.
Stay back from the front end of deck boats or raised platforms and remain seated while the boat is in motion.
Boats With Front‑Mounted, Raised Pedestal Fishing Seats
Elevated fishing seats are not intended for use when the boat is traveling faster than idle or trolling speed. Sit only in seats
designated for traveling at faster speeds.
Any unexpected, sudden reduction in boat speed could result in the elevated passenger falling over the front of the boat.
mc79557-1
Wave and Wake Jumping
WARNING
!
Wave or wake jumping can cause serious injury or death from occupants being thrown within or out of the boat. Avoid wave
or wake jumping whenever possible.
mc79680-1
Operating recreational boats over waves and wakes is a natural part of boating. However, when this activity is done with
enough speed to force the boat hull partially or completely out of the water, certain hazards arise, particularly when the boat
reenters the water.
The primary concern is the boat changing direction while in the midst of the jump. In such cases the landing may cause the
boat to violently veer in a new direction. Such a sharp change in direction or turn can cause occupants to be thrown out of their
seats or out of the boat.
There is another less common hazardous result from allowing your boat to launch off of a wave or wake. If the bow of your boat
pitches down far enough while airborne, upon water contact it may penetrate under the water surface and submarine for an
instant. This will bring the boat nearly to a stop in an instant and can send the occupants flying forward. The boat may also veer
sharply to one side.
90-8M0113857 eng DECEMBER 2015 Page 19
Section 2 - On the Water
Impact with Underwater Hazards
Reduce speed and proceed with caution whenever you're driving a boat in shallow water or in areas where the waters are
suspected of having underwater obstacles that could be struck by the underwater drive components, rudder, or the boat
bottom.
mc79679-1
IMPORTANT: The most important thing you can do to help reduce injury or impact damage from striking a floating or
underwater object is control the boat speed. Under these conditions, boat speed should be kept to a maximum speed of
24–40 km/h (15–25 mph).
Striking a floating/underwater object may result in an infinite number of situations. Some of these situations could result in the
following:
• The boat could move suddenly in a new direction. Such a sharp change in direction or turn can cause occupants to be
thrown out of their seats or out of the boat.
• A rapid reduction in speed. This will cause occupants to be thrown forward, even out of the boat.
• Impact damage to the underwater drive components, rudder, and/or boat.
Keep in mind, one of the most important things you can do to help reduce injury or impact damage in these situations is control
the boat speed. Boat speed should be kept to a minimum planing speed when driving in waters known to have underwater
obstacles.
After striking a submerged object, stop the engine as soon as possible and inspect the drive system for any broken or loose
parts. If damage is present or suspected, the power package should be taken to an authorized Mercury MerCruiser dealer for a
thorough inspection and necessary repair.
The boat should be checked for hull fractures, transom fractures, and water leaks.
Operating with damaged underwater drive components, rudder, or boat bottom could cause additional damage to other parts of
the power package, or could affect control of the boat. If continued operation is necessary, do so at greatly reduced speeds.
WARNING
!
Operating a boat or engine with impact damage can result in product damage, serious injury, or death. If the vessel
experiences any form of impact, have an authorized Mercury Marine dealer inspect and repair the vessel or power package.
Drive Unit Impact Protection
The power trim hydraulic system is designed to provide impact protection for the sterndrive unit. If a submerged object is struck
while the boat is moving forward, the hydraulic system will cushion the kickup of the sterndrive unit as it clears the object,
reducing damage to the unit. After the sterndrive unit has cleared the object, the hydraulic system allows the sterndrive unit to
return to its original operating position, preventing loss of steering control and engine overspeed.
Use extreme caution when operating in shallow water or where underwater objects are known to be present. No impact
protection is provided in reverse; use extreme care to prevent striking submerged objects while operating in reverse.
IMPORTANT: Impact protection system cannot be designed to ensure total protection from impact damage under all
conditions.
Page 20 90-8M0113857 eng DECEMBER 2015
Operating with Low Water Inlets in Shallow Water
a - Low water inlets
Section 2 - On the Water
a
mc75827-1
NOTICE
Operating in shallow water can cause severe engine damage due to clogged water inlets. Ensure that the water inlets on the
gearcase do not ingest sand, silt, or other debris, which can restrict or stop cooling water supply to the engine.
Extreme care should be exercised when operating a boat equipped with low water inlets while maneuvering in shallow water.
Also, avoid beaching a boat with the engine operating.
Conditions Affecting Operation
Weight Distribution (Passengers and Gear) Inside the Boat
Shifting weight to rear (stern):
• Generally increases speed and engine RPM
• Causes bow to bounce in choppy water
• Increases danger of following wave splashing into the boat when coming off plane
• At extremes, can cause the boat to porpoise
Shifting weight to front (bow):
• Improves ease of planing
• Improves rough water ride
• At extremes, can cause the boat to veer back and forth (bow steer)
The Bottom of the Boat
To maintain maximum speed, the boat bottom should be:
• Clean, free of barnacles and marine growth
• Free of distortion; nearly flat where it contacts the water
• Straight and smooth, fore and aft
Marine vegetation may accumulate when the boat is docked. This growth must be removed before operation; it may clog the
water inlets and cause the engine to overheat.
Cavitation
Cavitation occurs when water flow cannot follow the contour of a fast‑moving underwater object, such as a gear housing or a
propeller. Cavitation increases propeller speed while reducing boat speed. Cavitation can seriously erode the surface of the
gear housing or the propeller. Common causes of cavitation are:
• Weeds or other debris snagged on the propeller
• Bent propeller blade
• Raised burrs or sharp edges on the propeller
Ventilation
Ventilation is caused by surface air or exhaust gases that are introduced around the propeller resulting in propeller speed‑up
and a reduction in boat speed. Air bubbles strike the propeller blade and cause erosion of the blade surface. If allowed to
continue, eventual blade failure (breakage) will occur. Excessive ventilation is usually caused by:
• Drive unit trimmed out too far
• A missing propeller diffuser ring
90-8M0113857 eng DECEMBER 2015 Page 21
Section 2 - On the Water
• A damaged propeller or gear housing, which allows exhaust gases to escape between propeller and gear housing
• Drive unit installed too high on transom
Elevation and Climate
Elevation and climate changes will affect the performance of your power package. Loss of performance can be caused by:
• Higher elevations
• Higher temperatures
• Low barometric pressures
• High humidity
For you to have optimum engine performance under changing weather conditions, it is essential that the engine be propped to
allow the engine to operate at or near the top end of the specified maximum RPM range with a normal boat load during your
normal boating weather conditions.
In most cases, recommended RPM can be achieved by changing to a lower pitch propeller.
Propeller Selection
IMPORTANT: The engines covered in this manual are equipped with an RPM rev‑limiter that is set to an upper RPM limit. This
limit, which is slightly above the normal operating range of the engine, helps prevent damage from excessive engine RPM.
Once the RPM returns to the recommended operating RPM range, normal engine operation resumes.
The boat manufacturer and the selling dealer are responsible for equipping the power package with the correct propeller. Refer
to Mercury Marine's web page https://www.mercurymarine.com/en/us/propellers/selector/#/step‑one
Select a propeller that will allow the engine power package to operate at or near the top end of the recommended WOT
operating RPM range with a normal load.
If full‑throttle operation is below the recommended range, the propeller must be changed to prevent loss of performance and
possible engine damage. On the other hand, operating an engine above the recommended operating RPM range will cause
higher than normal wear and damage.
After initial propeller selection, the following common problems may require that the propeller be changed to a lower pitch.
• Warmer weather and greater humidity cause a loss of RPM.
• Operating in a higher elevation causes a loss of RPM.
• Operating with a dirty boat bottom causes a loss of RPM.
• Operating with increased load (additional passengers, pulling skiers) causes a loss of RPM.
For better acceleration, such as is needed for waterskiing, use the next lower pitch propeller. When not pulling skiers, do not
operate at full throttle when using the lower pitch propeller.
.
Getting Started
20‑Hour Break‑In Period
IMPORTANT: The first 20 hours of operation is the engine break‑in period. Correct break‑in is essential to obtain minimum oil
consumption and maximum engine performance. During this break‑in period, the following rules must be observed:
• Do not operate below 1500 RPM for extended periods of time for the first 10 hours. Shift into gear as soon as possible after
starting and advance the throttle above 1500 RPM if conditions permit safe operation.
• Do not operate at one speed consistently for extended periods.
• Do not exceed 3/4 throttle during the first 10 hours. During the next 10 hours, occasional operation at full throttle is
permissible (five minutes at a time maximum).
• Avoid full throttle acceleration from idle speed.
• Do not operate at full throttle until the engine reaches normal operating temperature.
• Frequently check engine oil level. Add oil as needed. It is normal for oil consumption to be high during the break‑in period.
After Break‑In Period
To help extend the life of your Mercury MerCruiser power package, follow these recommendations:
• Ensure that the propeller allows the engine to operate at or near the top of the specified WOT RPM range. Refer to
Specifications and Maintenance.
• Operate the engine at 3/4 throttle or lower. Refrain from prolonged operation at wide‑open throttle RPM.
•
Change the engine oil and oil filter. Refer to Maintenance.
•
Change the transmission oil and filter. Refer to Maintenance (ZF Transmission models).
1. Require fluid and filter change after the first 25 hours and then every 100 hours.
1.
Page 22 90-8M0113857 eng DECEMBER 2015
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