MerCruiser 8.1 H.O. User manual

© 2008 Mercury Marine 8.1 H.O. & Horizon 8.1 Models *864841070* 90-864841070 1007
NOTE: The following applies to CE marked products only.
Declaration of Conformance – Mercury MerCruiser
This sterndrive or inboard engine when installed in accordance to Mercury
MerCruisers’ instructions complies with the requirements of the following directives
by meeting the associated standards, as amended:
Recreational Craft Directive 94/25/EC; 2003/44/EC
Applicable Requirement Standards Applied
Owner’s manual (A.2.5) ISO 10240
Openings in Hull, Deck and superstructure (A.3.4) ISO 9093‑1; ISO 9093‑2
Handling characteristics (A.4) ISO 8665
Inboard Engine (A.5.1.1) ISO 15584; ISO 10088; ISO 7840; ISO 10133
Fuel System (A.5.2) ISO 10088; ISO 7840; ISO 8469
Electrical System (A.5.3) ISO 10133; ISO 8846
Steering system (A.5.4) Applicable portions of: ISO 10592, ISO 8848 and
ABYC P‑17
Exhaust emission requirements (B.2) ISO 8178
Owner’s manual (B.4) ISO 8665
Noise emission levels (C.1) ISO 14509
Ignition‑protected equipment (Annex II) ISO 8846; SAE J1171; SAE J1191; SAE J 2031
Mercury MerCruiser declares that our sterndrive or inboard engines without integral
exhaust, when installed in a recreational craft, in accordance with the manufacturers
supplied instructions, will meet the exhaust emissions requirements of the directive
mentioned above. This engine must not be put into service until the recreational craft
in which it is to be installed has been declared in conformity, if so required, with the
relevant provision of the directive.
Electromagnetic Compatibility Directive 89/336/EC, 92/31/EEC and 93/68/EEC
Generic emission standard EN 50081‑1
Generic immunity standard EN 50082‑1
Vehicles, boats and internal combustion engine
driven devices ‑ Radio disturbance characteristics SAE J551 (CISPR 12)
Electrostatic discharge testing EN 61000‑6‑2; EN 61000‑4‑2; EN61000‑4‑3
The notified body responsible for surveillance of the quality system under Full Quality Assurance
Module H of Directive 2003/44/EC is:
Det Norske Veritas
Norway
Notified Body Number: 0575
This declaration is issued under the sole responsibility of Mercury Marine and Mercury MerCruiser.
Kevin Grodzki
President ‑ Mercury MerCruiser, Stillwater, OK, USA

Regulatory contact:
Regulations and Product Safety Department
Mercury Marine
W6250 W. Pioneer Road
Fond du Lac, WI 54936
USA
Identification Record
Please record the following information:
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
The serial numbers are the manufacturer’s keys to numerous engineering details that apply
to your Mercury MerCruiser® power package. When contacting your Authorized Mercury
MerCruiser Dealer about service, always specify model and serial numbers.
The description and specifications contained herein were in effect at the time this guide
was approved for printing. Mercury Marine, whose policy is one of continuous
improvement, reserves the right to discontinue models at any time, or to change
specifications or designs, without notice and without incurring obligation.
Mercury Marine, Fond du Lac, Wisconsin, U.S.A. Printed in U.S.A.
© 2008, Mercury Marine
Mercury, Mercury Marine, MerCruiser, Mercury MerCruiser, Mercury Racing, Mercury
Precision Parts, Mercury Propellers, Mariner, Quicksilver, #1 On The Water, Alpha, Bravo,
Bravo Two, Pro Max, OptiMax, Sport‑Jet, K‑Planes, MerCathode, RideGuide, SmartCraft,
Zero Effort, M with Waves logo, Mercury with Waves logo, VesselView, and SmartCraft
logo are all registered trademarks of Brunswick Corporation. Mercury Product Protection
logo is a registered service mark of Brunswick Corporation.
Welcome
You have selected one of the finest marine power packages available. It incorporates
numerous design features to assure operating ease and durability.
With proper care and maintenance, you will thoroughly 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, Maintenance and Warranty 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 Mercury MerCruiser products. We sincerely hope your
boating will be pleasant!
Mercury MerCruiser
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 Sections of this manual. The warranty
statement 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.
Mercury Marine products are designed and manufactured to comply with our own high
quality standards, applicable industry standards and regulations, as well as certain
emissions regulations. At Mercury Marine every engine is operated and tested before it is
boxed for shipment to make sure that the product is ready for use. In addition, certain
Mercury Marine products are tested in a controlled and monitored environment, for up to
10 hours of engine run time, in order to verify and make a record of compliance with
applicable standards and regulations. All Mercury Marine product, sold as new, receives
the applicable limited warranty coverage, whether the engine participated in one of the test
programs described above or not.
Read This Manual Thoroughly
IMPORTANT: If you don’t understand any portion of this manual, contact your dealer for a
demonstration of actual starting and operating procedures.
Notice
Throughout this publication, and on your power package, dangers, warnings, cautions, and
notices, accompanied by the International Hazard Symbol !, may be used to alert the
installer/user to special instructions concerning a particular service or operation that may
be hazardous if performed incorrectly or carelessly. These safety alerts follow ANSI
standard Z535.6‑2006 for product safety information in product manuals, instructions, and
other collateral materials. 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.
! DANGER
Indicates a hazardous situation which, if not avoided, will result in death or serious injury.
! 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.
! WARNING
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, Maintenance and Warranty 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.

90-864841070 OCTOBER 2007 Page i
TABLE OF CONTENTS
Section 1 - Warranty
Warranty Registration: United States and
Canada....................................................................2
Warranty Registration: Outside the United States and
Canada....................................................................2
Transfer of Warranty................................................3
Mercury Product Protection Plan: United States and
Canada....................................................................3
Mercury MerCruiser Limited Warranty
(Gasoline‑Fueled Products Only) ‑ USA & Canada
(For other countries please refer to the chart) ........4
3‑Year Limited Warranty Against Corrosion............6
Global Warranty Charts...........................................7
Consumer Application Warranty Chart...............7
Commercial Application Warranty Chart.............8
Government Application Warranty Chart............9
Mercury Installation Quality Certification Program..9
Emission Control Information Label.......................10
Owner Responsibility........................................11
Section 2 - Getting to Know Your Power Package
Identification..........................................................14
Engine Serial Number Decal..........................14
Lanyard Stop Switch..............................................14
Instrumentation......................................................15
Digital Gauges..................................................15
Analog Gauges.................................................16
Remote Controls (Non‑DTS Models).....................16
Remote Controls............................................16
Panel Mount Features..................................17
Console Mount Features..............................18
Zero Effort Features.......................................18
Remote Controls (DTS Models)............................19
Remote Controls............................................19
Panel Mount Features....................................19
Console Mount Features ‑ Single Engine.......20
Slim Binnacle Console Mount Features ‑ Single
Engine............................................................21
Console Mount Features‑ Dual Engine..........22
Synchronizing Dual Engines..........................22
Dual Helm Station Transfer............................23
Synchronizing Dual Helms Prior To Station
Transfer........................................................24
Zero Effort Features.......................................24
Electrical System Overload Protection..................24
Audio Warning System..........................................26
Testing The Audio Warning System.................27
Engine Guardian Strategy.....................................27
Transmission Guardian Strategy...........................27
Warning Horn Signals............................................28
Section 3 - On the Water
Safe Boating Suggestions.....................................30
Be Alert to Carbon Monoxide Poisoning................31
Good Ventilation...............................................31
Poor Ventilation ...............................................32
Basic Boat Operation (Non‑DTS Models)..............32
Launching and Boat Operation.......................32
Operation Chart............................................32
Starting and Stopping the Engine...................33
Starting the Engine.......................................33
Stopping the Engine.....................................34
Throttle‑Only Operation..................................34
Freezing Temperature Operation...................34
Drain Plug and Bilge Pump............................34
Basic Boat Operation (DTS Models).....................34
Launching and Boat Operation.......................34
Operation Chart............................................34
Starting and Stopping the Engine...................35
Starting the Engine.......................................35
Stopping the Engine.....................................36
Throttle‑Only Operation..................................36
Freezing Temperature Operation...................37
Drain Plug and Bilge Pump............................37
Protecting People in the Water..............................37
While You Are Cruising.....................................37
While Boat Is Stationary...................................37
High‑Speed and High‑Performance Operation......38

Page ii 90-864841070 OCTOBER 2007
Passenger Safety in Pontoon Boats and Deck
Boats.................................................................... 38
Boats Having An Open Front Deck..................38
Boats With Front‑Mounted, Raised Pedestal
Fishing Seats...................................................38
Wave and Wake Jumping.................................... 39
Impact with Underwater Hazards......................... 39
Conditions Affecting Operation.............................40
Weight Distribution (Passengers and Gear)
Inside the Boat.............................................. 40
The Bottom of the Boat................................. 40
Cavitation...................................................... 40
Ventilation..................................................... 41
Elevation and Climate................................... 41
Getting Started..................................................... 41
20‑Hour Break‑In Period............................... 41
After Break‑In Period.....................................41
End of First Season Checkup....................... 42
Section 4 - Specifications
Cruising RPM....................................................... 44
Fuel Requirements...............................................44
Fuel Ratings.....................................................44
Using Reformulated (Oxygenated) Gasolines
(USA Only).......................................................44
Gasolines Containing Alcohol..........................44
Engine Oil.............................................................45
Engine Specifications...........................................46
Fluid Specifications.............................................. 47
Transmission................................................... 47
Engine..............................................................47
Section 5 - Maintenance
Owner/Operator Responsibilities..........................50
Dealer Responsibilities.........................................50
Maintenance.........................................................50
Do‑It‑Yourself Maintenance Suggestions.............51
Inspection.............................................................51
Maintenance Schedule—Inboard Models............ 52
Routine Maintenance.................................... 52
Scheduled Maintenance................................52
Maintenance Log..................................................53
Engine Oil.............................................................53
Checking..........................................................53
Filling............................................................... 54
Changing Oil and Filter....................................55
Engine Oil Drain Pump............................... 55
Changing Filter............................................56
Transmission Fluid............................................... 56
Checking While the Engine is Warm............... 56
Checking While Engine is Cold........................57
Changing......................................................... 57
Engine Coolant.....................................................57
Checking..........................................................57
Filling............................................................... 58
Changing ........................................................ 58
Changing the Water‑Separating Fuel Filter..........58
Cleaning the Flame Arrestor................................ 60
Serpentine Drive Belt........................................... 61
Checking..........................................................61
Replacing.........................................................61
Flushing the Seawater System—Inboard
Models..................................................................63
The Boat out of the Water—Inboard Models.63
The Boat in the Water—Inboard Models.......64
Battery..................................................................65
Multiple EFI Engine Battery Precautions.......65
Section 6 - Storage
Cold Weather or Extended Storage..................... 68
Preparing Power Package for Storage..........68
Engine and Fuel System Preparation......... 69
Draining the Seawater System.............................70
Drain System Identification........................... 70
Air Actuated Single Point Drain System......70
Manual Drain System..................................71
Air Actuated Single Point Drain System........71
Boat in the Water........................................ 71
Boat out of the Water..................................73
Manual Drain System....................................75
Boat in the Water........................................ 75
Boat out of the Water..................................76
Battery Storage.................................................... 77

90-864841070 OCTOBER 2007 Page iii
Power Package Recommissioning........................77
Section 7 - Troubleshooting
Diagnosing EFI Problems......................................80
Diagnosing DTS Problems....................................80
Engine Guardian System.......................................80
Starter Motor Will Not Crank Engine, Or Cranks
Slow.......................................................................80
Engine Will Not Start or Is Hard to Start................81
Engine Runs Rough, Misses, or Backfires............81
Poor Performance.................................................81
Excessive Engine Temperature.............................81
Insufficient Engine Temperature............................82
Low Engine Oil Pressure.......................................82
Battery Will Not Recharge.....................................82
Remote Control Is Difficult to Move, Has Excessive
Play, or Makes Unusual Sounds...........................83
Steering Wheel Jerks or Is Difficult to Turn...........83
Section 8 - Customer Assistance Information
Owner Service Assistance.....................................86
Local Repair Service.........................................86
Service Away From Home................................86
Stolen Power Package.....................................86
Attention Required after Submersion................86
Replacement Service Parts..............................86
Parts and Accessories Inquiries...................87
Resolving a Problem.........................................87
Mercury Marine Service Offices........................87
Ordering Literature................................................88
United States and Canada................................88
Outside The United States and Canada...........88

Page iv 90-864841070 OCTOBER 2007

Section 1 - Warranty
90-864841070 OCTOBER 2007 Page 1
Section 1 - Warranty
Table of Contents
Warranty Registration: United States and Canada
.............................................................................. 2
Warranty Registration: Outside the United States
and Canada.......................................................... 2
Transfer of Warranty............................................. 3
Mercury Product Protection Plan: United States and
Canada................................................................. 3
Mercury MerCruiser Limited Warranty (Gasoline-
Fueled Products Only) - USA & Canada (For other
countries please refer to the chart) ...................... 4
3-Year Limited Warranty Against Corrosion......... 6
Global Warranty Charts........................................ 7
Consumer Application Warranty Chart ........... 7
Commercial Application Warranty Chart ........ 8
Government Application Warranty Chart ....... 9
Mercury Installation Quality Certification Program
.............................................................................. 9
Emission Control Information Label.................... 10
Owner Responsibility ................................... 11
1

Section 1 - Warranty
Page 2 90-864841070 OCTOBER 2007
Warranty Registration: United States and Canada
To ensure that your warranty coverage begins promptly, your selling dealer should fill out
the Warranty Registration Card completely and mail it to the factory immediately upon sale
of the new product.
The Warranty Registration Card identifies the name and address of the original purchaser,
product model and serial number(s), date of sale, type of use and selling dealer’s code,
name, and address. The dealer also certifies that you are the original purchaser and user
of the product. A temporary Owner Warranty Registration Card will be presented to you
when you purchase the product.
Upon receipt of the Warranty Registration Card at the factory, Mercury MerCruiser will send
you an owner resource guide that includes your warranty registration confirmation. If you
do not receive your owner resource guide within 60 days from date of new product sale,
please contact your selling dealer.
Because of your selling dealer’s ongoing interest in your satisfaction, the product should
be returned to him for warranty service.
The product warranty is not effective until the product is registered at the factory.
NOTE: Registration lists must be maintained by the factory and dealer on marine products
sold in the United States in the event that a safety recall notification under the Federal Boat
Safety Act is required.
You may change your address at any time, including at time of warranty claim, by calling
Mercury MerCruiser or sending a letter or fax to Mercury MerCruiser’s warranty registration
department with your name, old address, new address, and engine serial number. Your
dealer can also process this change of information.
United States customers or dealers may contact:
Mercury Marine
Attn: Warranty Registration Department
W6250 Pioneer Road
P.O. Box 1939
Fond du Lac, WI 54936-1939
920-929-5054
Fax [phone]
Canadian customers or dealers may contact:
Mercury Marine Canada Limited
2395 Meadowpine Blvd.
Mississauga, ON
Canada, L5N 7W6
Fax [phone]
Warranty Registration: Outside the United States and Canada
To ensure that your warranty coverage begins promptly, your selling dealer should fill out
the warranty registration card completely and mail it to the distributor responsible for
administering the warranty registration and claim program for your area.