Mercury 225, 225 EFI, 3.0 Litre SeaPro, 250 EFI, 3.0 Litre Marathon Service Manual
SERVICE
MANUAL
MODELS
225 • 225 EFI • 250 EFI • 3.0 Litre
Marathon • 3.0 Litre SeaPro
With Serial Numbers
United States 0D280813 and Above. . .
1997, Mercury Marine
90-822900R3 DECEMBER 1997Printed in U.S.A.
Notice
Throughout this publication, “Dangers”, “Warnings”
and “Cautions” (accompanied by the International
HAZARD Symbol
to special instructions concerning a particular service
or operation that may be hazardous if performed incorrectly or carelessly.
FULLY!
These “Safety Alerts” alone cannot eliminate the hazards that they signal. Strict compliance to these special instructions when performing the service, plus
“Common Sense” operation, are major accident prevention measures.
DANGER - Immediate hazards which WILL result
in severe personal injury or death.
) are used to alert the mechanic
OBSERVE THEM CARE-
DANGER
who uses a service procedure and/or tool, which is
not recommended by the manufacturer, first must
completely satisfy himself that neither his nor the
products safety will be endangered by the service
procedure selected.
All information, illustrations and specifications contained in this manual are based on the latest product
information available at the time of publication. As required, revisions to this manual will be sent to all dealers contracted by us to sell and/or service these products.
It should be kept in mind, while working on the product, that the electrical system and ignition system are
capable of violent and damaging short circuits or severe electrical shocks. When performing any work
where electrical terminals could possibly be
grounded or touched by the mechanic, the battery
cables should be disconnected at the battery.
WARNING
WARNING - Hazards or unsafe practices which
COULD result in severe personal injury or death.
CAUTION
Hazards or unsafe practices which could result
in minor personal injury or product or property
damage.
Notice to Users of This
Manual
This service manual has been written and published
by the Service Department of Mercury Marine to aid
our dealers’ mechanics and company service personnel when servicing the products described herein.
It is assumed that these personnel are familiar with
the servicing procedures of these products, or like or
similar products manufactured and marketed by
Mercury Marine, that they have been trained in the
recommended servicing procedures of these products which includes the use of mechanics’ common
hand tools and the special Mercury Marine or recommended tools from other suppliers.
Any time the intake or exhaust openings are exposed
during service they should be covered to protect
against accidental entrance of foreign material which
could enter the cylinders and cause extensive internal damage when the engine is started.
It is important to note, during any maintenance procedure replacement fasteners must have the same
measurements and strength as those removed.
Numbers on the heads of the metric bolts and on the
surfaces of metric nuts indicate their strength. American bolts use radial lines for this purpose, while most
American nuts do not have strength markings. Mismatched or incorrect fasteners can result in damage
or malfunction, or possibly personal injury. Therefore, fasteners removed should be saved for reuse in
the same locations whenever possible. Where the
fasteners are not satisfactory for re-use, care should
be taken to select a replacement that matches the
original.
We could not possibly know of and advise the service
trade of all conceivable procedures by which a service might be performed and of the possible hazards
and/or results of each method. We have not undertaken any such wide evaluation. Therefore, anyone
i90-822900R3 DECEMBER 1997
Cleanliness and Care of
Outboard Motor
A marine power product is a combination of many
machined, honed, polished and lapped surfaces with
tolerances that are measured in the ten thousands of
an inch./mm. When any product component is serviced, care and cleanliness are important. Throughout
this manual, it should be understood that proper
cleaning, and protection of machined surfaces and
friction areas is a part of the repair procedure. This is
considered standard shop practice even if not specifically stated.
Whenever components are removed for service,
they should be retained in order. At the time of installation, they should be installed in the same locations
and with the same mating surfaces as when removed.
Before raising or removing and outboard engine from
a boat, the following precautions should be adhered
to:
1. Check that flywheel is secured to end of crankshaft with a locknut and lifting eye is threaded into
flywheel a minimum of 5 turns.
In addition, personnel should not work on or under an
outboard which is suspended. Outboards should be
attached to work stands, or lowered to ground as
soon as possible.
We reserve the right to make changes to this manual
without prior notification.
Refer to dealer service bulletins for other pertinent information concerning the products described in this
manual.
Page Numbering
Two number groups appear at the bottom of each
page. The example below is self-explanatory.
2. Connect a hoist of suitable strength to the lifting
eye.
EXAMPLE:
90-826148 R1 JANUARY 1993
LOWER UNIT - 6A-7
Revision No. 1
Month of Printing
Year of Printing
Section Description
Section Number
Part of Section Letter
Page Number
ii 90-822900R3 DECEMBER 1997
Service Manual Outline
Section 1 - Important Information
A - Specifications
B - Maintenance
C - General Information
D - Outboard Installation
Section 2 - Electrical
A - Ignition
B - Charging & Starting System
C - Timing, Synchronizing & Adjusting
D - Wiring Diagrams
Section 3 - Fuel System
A - Fuel Pump
B - Carburetor
C - Fuel Injection
D - Oil Injection
E - Emissions
Section 4 - Powerhead
Section 5 - Mid-Section
A - Clamp/Swivel Brackets & Drive Shaft Housing
B - Power Trim
Section 6 - Lower Unit
A - Right Hand Rotation
B - Left Hand Rotation
Section 7 - Attachments/Control Linkage
Important
Information
1
Electrical
2
Fuel System
3
Powerhead
4
Mid-Section
5
Lower Unit
6
Attachments/
Control Linkage
7
90-822900R3 DECEMBER 1997
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