Mariner 225 User manual

MODELS
225 •225 EFI •250 EFI •3.0 Litre
Marathon •3.0 Litre SeaPro
United States 0D280813 and Above. . .
With Serial Numbers
SERVICE
MANUAL
90-822900R3 DECEMBER 1997Printed in U.S.A. 1997, Mercury Marine

i90-822900R3 DECEMBER 1997
Notice
Throughout this publication, “Dangers”, “Warnings”
and “Cautions” (accompanied by the International
HAZARDSymbol )areusedtoalertthemechanic
tospecialinstructionsconcerningaparticularservice
or operation that may be hazardous if performed in-
correctly or carelessly. OBSERVE THEM CARE-
FULLY!
These“SafetyAlerts”alonecannoteliminatethehaz-
ards that they signal. Strict compliance to these spe-
cial instructions when performing the service, plus
“Common Sense” operation, are major accident pre-
vention measures.
DANGER
DANGER - Immediate hazards which WILL result
in severe personal injury or death.
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 per-
sonnel when servicing the products described here-
in.
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 prod-
ucts which includes the use of mechanics’ common
handtools andthe specialMercuryMarineorrecom-
mended tools from other suppliers.
Wecouldnotpossiblyknowofandadvisetheservice
trade of all conceivable procedures by which a ser-
vice might be performed and of the possible hazards
and/or results of each method. We have not under-
taken any such wide evaluation. Therefore, anyone
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 con-
tained in this manual are based on the latest product
informationavailableatthetimeofpublication.Asre-
quired,revisionstothismanualwillbesenttoalldeal-
erscontractedbyustoselland/orservicetheseprod-
ucts.
It should be kept in mind, while working on the prod-
uct,thattheelectricalsystemand ignitionsystemare
capable of violent and damaging short circuits or se-
vere 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.
Anytimetheintakeorexhaustopeningsareexposed
during service they should be covered to protect
againstaccidentalentranceofforeignmaterialwhich
could enter the cylinders and cause extensive inter-
nal damage when the engine is started.
Itisimportanttonote,duringanymaintenanceproce-
dure replacement fasteners must have the same
measurements and strength as those removed.
Numbers on the heads of the metric bolts and on the
surfacesofmetricnutsindicatetheirstrength.Ameri-
canbolts use radial lines for this purpose, while most
American nuts do not have strength markings. Mis-
matched or incorrect fasteners can result in damage
or malfunction, or possibly personal injury. There-
fore,fasteners removed shouldbesavedfor 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.

ii 90-822900R3 DECEMBER 1997
Cleanliness and Care of
Outboard Motor
A marine power product is a combination of many
machined,honed,polishedandlappedsurfaceswith
tolerancesthat are measuredintheten thousands of
an inch./mm. When any product component is serv-
iced,careandcleanlinessareimportant.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
consideredstandardshoppracticeevenifnotspecif-
ically stated.
Whenever components are removed for service,
they should be retained in order. At the time of instal-
lation, they should be installed in the same locations
and with the same mating surfaces as when re-
moved.
Beforeraisingorremovingandoutboardenginefrom
a boat, the following precautions should be adhered
to:
1. Check that flywheel is secured to end of crank-
shaftwithalocknutandliftingeyeisthreadedinto
flywheel a minimum of 5 turns.
2. Connect a hoist of suitable strength to the lifting
eye.
Inaddition,personnelshouldnotworkonorunderan
outboard which is suspended. Outboards should be
attached to work stands, or lowered to ground as
soon as possible.
Wereserve the right to make changesto this manual
without prior notification.
Refertodealerservicebulletinsforotherpertinentin-
formation 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.
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

Important
Information
Electrical
Fuel System
Powerhead
Mid-Section
Lower Unit
Attachments/
Control Linkage
1
2
3
4
5
6
7
iii
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