Mercury 25 Series User manual

i
Thank You
for your purchase of one of the finest outboards available. You
have made a sound investment in boating pleasure. Your
outboard has been manufactured by Mercury Marine, a world
leader in marine technology and outboard manufacturing
since 1939. These years of experience have been committed
to the goal of producing the finest quality products. This led to
Mercury Marine's reputation for strict quality control,
excellence, durability, lasting performance and being the best
at providing after the sale support.
Please read this manual carefully before operating your
outboard. This manual has been prepared to assist you in the
operation, safe use and care of your outboard.
All of us at Mercury Marine took pride in building your outboard
and wish you many years of happy and safe boating.
Again, thank you for your confidence in Mercury Marine.
EPA Emissions Regulations
Outboards sold by Mercury Marine in the United States are
certified to the United States Environmental Protection
Agency as conforming to the requirements of the regulations
for the control of air pollution from new outboard motors. This
certification is contingent on certain adjustments being set to
factory standards. For this reason, the factory procedure for
servicing the product must be strictly followed and, wherever
practicable, returned to the original intent of the design.
Maintenance, replacement, or repair of the emission
control devices and systems may be performed by any
marine engine repair establishment or individual.
Engines are labeled with an Emission Control Information
decal as permanent evidence of EPA certification.
! WARNING
The engine exhaust from this product contains chemicals
known to the state of California to cause cancer, birth defects
or other reproductive harm.
© 2008 Mercury Marine 25/30 2-Stroke 90-10261080 1008

ii
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 Information Section 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.
The description and specifications contained herein were in effect
at the time this manual was approved for printing. Mercury Marine,
whose policy is one of continued improvement, reserves the right
to discontinue models at any time, to change specifications,
designs, methods, or procedures without notice and without
incurring obligation.
Mercury Marine, Fond du Lac, Wisconsin U.S.A.
Litho 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, Pro Max,
OptiMax, Sport‑Jet, K‑Planes, MerCathode, RideGuide,
SmartCraft, Zero Effort, M with Waves logo, Mercury with Waves
logo, and SmartCraft logo are all registered trademarks of
Brunswick Corporation. Mercury Product Protection logo is a
registered service mark of Brunswick Corporation.
Declaration of Conformity
If the outboard motor’s serial number plate contains the CE mark
in the lower left‑hand corner, the following statement applies:
This outboard motor manufactured by Mercury Marine, Fond du
Lac, WI, USA or Marine Power Europe Inc. Park Industriel, de
Petit‑Rechain, Belgium complies with the requirements of the
following directives and standards, as amended:
Recreational Craft Directive: 94/25/EC
Owner's manual (A.2.5) ISO 10240

iii
Handling characteristics (A.4) ISO 8665
Outboard engine starting (A.5.1.4) ISO 11547
Fuel tanks (A.5.2.2) ISO 13591; ISO 8469
General steering system ABYC P‑17
Safety of Machinery Directive 98/37/EC
Principles of safety integration
(1.1.2) EN 292‑1; EN 292‑2; EN 1050
Noise (1.5.8) ICOMIA 39/94
Vibration ICOMIA 38/94
Electromagnetic Compatibility
Directive 89/336/EC
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; EN
61000‑4‑3
This declaration is issued under the sole responsibility of Mercury
Marine and Marine Power Europe.
Patrick C. Mackey
President, Mercury Marine, Fond du Lac, WI USA
European Regulations Contact:
Regulations and Product Safety Department, Mercury Marine,
Fond du Lac, WI USA

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Mercury Premier Service
Mercury evaluates the service performance of its dealers and
assigns its highest rating of "Mercury Premier" to those
demonstrating an exceptional commitment to service.
Earning a Mercury Premier Service rating means a dealer:
• Achieves a high 12 month service CSI (Customer Satisfaction
Index) score for warranty service.
• Possesses all necessary service tools, test equipment,
manuals and parts books.
• Employs at least one Certified or Master technician.
• Provides timely service for all Mercury Marine customers.
• Offers extended service hours and mobile service, when
appropriate.
• Uses, displays and stocks adequate inventory of genuine
Mercury Precision Parts.
• Offers a clean, neat shop with well organized tools and service
literature.

TABLE OF CONTENTS
v
Warranty Information
Transfer of Warranty....................................................................1
Transfer of Mercury Product Protection (Extended Service
Coverage) Plan............................................................................1
Warranty Registration United States And Canada......................2
Outboard Limited Warranty..........................................................3
3 Year Limited Warranty Against Corrosion................................6
Warranty Coverage and Exclusions............................................9
GENERAL INFORMATION
Boater's Responsibilities............................................................12
Before Operating Your Outboard...............................................12
Boat Horsepower Capacity........................................................13
High‑Speed and High‑Performance Boat Operation................. 13
Outboard Remote Control Models.............................................13
Remote Steering Notice.............................................................14
Lanyard Stop Switch..................................................................15
Protecting People in the Water..................................................17
Passenger Safety Message ‑ Pontoon Boats and Deck Boats..18
Wave and Wake Jumping..........................................................19
Impact with Underwater Hazards...............................................20
Exhaust Emissions.................................................................... 21
Selecting Accessories for Your Outboard..................................23
Safe Boating Suggestions......................................................... 23
Recording Serial Number.......................................................... 25
25/30 Specifications...................................................................26
Components: 25/30M................................................................ 27
INSTALLATION
Installing Outboard.....................................................................34
Installing the Remote Control Device (Right‑Hand Steering).... 36
Attaching the Steering Link Rod................................................45
Battery Installation ....................................................................46
Propeller Selection.....................................................................48

TABLE OF CONTENTS
vi
TRANSPORTING
Trailering Boat/Outboard...........................................................49
Removing the Motor..................................................................49
Transporting Portable Fuel Tanks.............................................50
FUEL & OIL
Fuel Recommendations.............................................................52
Oil Recommendation.................................................................53
Mixing Fuel and Oil....................................................................54
Filling Fuel Tank........................................................................54
FEATURES & CONTROLS
Remote Control Features..........................................................56
Tilting Outboard ........................................................................56
Shallow Water Operation...........................................................57
Trim Adjustment.........................................................................58
Steering Friction Adjustment......................................................59
Trim Tab Adjustment.................................................................60
OPERATION
Pre‑Starting Check List..............................................................62
Operating in Freezing Temperatures.........................................62
Operating in Saltwater or Polluted Water..................................62
Operating at High Elevations.....................................................63
Engine Break‑in Procedure........................................................63
Starting the Engine....................................................................64
Warm‑Up...................................................................................70
Gear Shifting..............................................................................71
Stopping the Engine..................................................................73
Emergency Starting...................................................................75

TABLE OF CONTENTS
vii
MAINTENANCE
Outboard Care...........................................................................77
EPA Regulations........................................................................77
EPA Emissions..........................................................................78
Inspection and Maintenance Schedule......................................78
Flushing the Cooling System.....................................................80
Top Cowl Removal and Installation...........................................81
Battery Inspection .....................................................................82
Fuel System...............................................................................82
Fuse Replacement ‑ Electric Start Remote Control Models......84
Corrosion Control Anode...........................................................84
Propeller Replacement..............................................................85
Spark Plug Inspection and Replacement...................................89
Lubrication Points......................................................................90
Gearcase Lubrication.................................................................90
Submerged Outboard................................................................92
STORAGE
Storage Preparation...................................................................93
Protecting External Outboard Components...............................94
Protecting Internal Engine Components....................................94
Gearcase...................................................................................95
Positioning Outboard for Storage..............................................95
Battery Storage..........................................................................95
TROUBLESHOOTING
Starter Motor Will Not Crank The Engine (Electric Start Models)
...................................................................................................96
Engine Will Not Start..................................................................96
Engine Runs Erratically.............................................................96
Performance Loss......................................................................97
Battery Will Not Hold Charge.....................................................97

TABLE OF CONTENTS
viii
ASSOCIATED PARTS
Associated Parts........................................................................98
ACCESSORIES
Accessories...............................................................................99
WIRING DIAGRAMS
Wiring Diagrams......................................................................103
OWNER SERVICE ASSISTANCE
Local Repair Service................................................................112
Service Away from Home........................................................112
Parts and Accessories Inquiries..............................................112
Service Assistance..................................................................112
Mercury Marine Service Offices...............................................113
MAINTENANCE LOG
Maintenance Log.....................................................................115

WARRANTY INFORMATION
1
Transfer of Warranty
The limited warranty is transferable to a subsequent purchaser, but
only for the remainder of the unused portion of the limited warranty.
This will not apply to products used for commercial applications.
To transfer the warranty to the subsequent owner, send or fax a
copy of the bill of sale or purchase agreement, new owner’s name,
address and engine serial number to Mercury Marine’s warranty
registration department. In the United States and Canada, mail to:
Mercury Marine
Attn: Warranty Registration Department
W6250 W. Pioneer Road
P.O. Box 1939
Fond du Lac, WI 54936-1939
920-929-5054
Fax [phone]
Upon processing the transfer of warranty, Mercury Marine will send
registration verification to the new owner of the product by mail.
There is no charge for this service.
For products purchased outside the United States and Canada,
contact the distributor in your country, or the Marine Power Service
Center closest to you.
Transfer of Mercury Product Protection (Extended
Service Coverage) Plan
The remaining coverage period of the Product Protection Plan is
transferable to the subsequent purchaser of the engine within thirty
(30) days from the date of sale. Contracts not transferred within
thirty (30) days of the subsequent purchase will no longer be valid
and the product will no longer be eligible for coverage under the
terms of the contract.
To transfer the plan to the subsequent owner, contact Mercury
Product Protection or authorized dealer to receive a Request for
Transfer form. Submit to Mercury Product Protection a receipt/bill
of sale, a completed Request of Transfer form, and a check
payable to Mercury Marine in the amount of $50.00 (per engine)
to cover the transfer fee.

WARRANTY INFORMATION
2
Plan coverage is not transferable from one product to another
product or for non‑eligible applications.
The Certified Pre‑Owned engine plans are not transferable.
For help or assistance, contact Mercury Product Protection
Department at 1‑888‑427‑5373 from 7:30 a.m. to 4:30 p.m. CST,
Monday ‑ Friday or email [email protected].
Warranty Registration United States And Canada
Outside United States and Canada ‑ Check with your local
distributor.
1. You may change your address at any time, including at time
of warranty claim, by calling Mercury Marine or sending a letter
or fax with your name, old address, new address, and engine
serial number to Mercury Marine’s warranty registration
department. Your dealer can also process this change of
information.
Mercury Marine
Attn: Warranty Registration Department
W6250 W. Pioneer Road
P.O. Box 1939
Fond du Lac, WI 54936-1939
920-929-5054
Fax [phone]
NOTE: Registration lists must be maintained by Mercury Marine
and any dealer on marine products sold in the United States,
should a safety recall notification under the Federal Safety Act be
required.
2. To be eligible for warranty coverage, the product must be
registered with Mercury Marine. At the time of sale, the dealer
should complete the warranty registration and immediately
submit it to Mercury Marine via MercNET, E‑mail, or mail.
Upon receipt of this warranty registration, Mercury Marine will
record the registration.