TOHATSU MFS 25C User manual

/".O
."

i
4st 25/30 2016
ÌÀ`ÕVÌ
ivÀiÊÀi>`}ÊÌÃÊ>Õ>
This service manual provides information that is needed for inspection, service and repair of
applicable outboard motors. For information about operation of the products that are not described
in this document, refer to the owners manual. For our customers' safe and dependable use of the
product for long term, it is essential to maintain the performance and quality of the outboard. To
ensure this, the maintenance and service have to be done properly by service technicians with
fundamental knowledge and skills. This manual is utilized so that our customers can always use their
outboard motor with full satisfaction.
Safety Information
Safety Statements
The following safety statements are found throughout this manual and indicate information
which, if ignored, could result in fatal safety hazards or property damage:
7,  
`V>ÌiÃÊ ÌiÊ «ÀiÃiViÊ vÊ >Ê >â>À`Ê ÀÊ >Ê
ÕÃ>viÊ >VÌÛÌÞÊ ÜV]Ê vÊ }Ài`]Ê VÕ`Ê
ÀiÃÕÌÊÊÃiÛiÀiÊÕÀÞÊÀÊ`i>Ì°
 ,
`V>ÌiÃÊ ÌiÊ «ÀiÃiViÊ vÊ >Ê >â>À`Ê ÜV]Ê
vÊ }Ài`]Ê ÜÊ ÀiÃÕÌÊ Ê ÃiÛiÀiÊ ÕÀÞÊ ÀÊ
`i>Ì°
1/"
`V>ÌiÃÊ ÌiÊ «ÀiÃiViÊ vÊ >Ê >â>À`Ê ÀÊ >Ê
ÕÃ>viÊ >VÌÛÌÞÊ ÜV]Ê vÊ }Ài`]Ê VÕ`Ê
ÀiÃÕÌÊÊÀÊ«iÀÃ>ÊÕÀÞÊÀÊ`>>}iÊÌÊ
ÌiÊ«À`ÕVÌÃÊÀÊv>VÌið
Attention:

4st 25/30 2016
LÕÌÊÌÃÊ>Õ>
This service manual is designed so that service persons are able to perform their work correctly.
Understand the following matters well for efficient repairs.
Each chapter begins with the introduction of special tools that are used for the work described in the
chapter so that the service persons are able to figure out the tools needed.
Parts that are serviced in each chapter and their details are presented by using a component composition
diagram.
Fastening torques are described in the component composition diagram and in the body text and are
critical points of the applicable repair.
Pictograms indicate that there is an important instruction for the relevant parts. It also shows the type of
lubricant and its application point(s).
The component composition diagrams describe the names of the parts, the quantity of the parts used,
size of fasteners and special notes.
Specific works are described in detail by using illustrations and adding advice on the work.
ÜiÀÊ1Ì
1/"
ÊÌÊÀiÕÃiÊÀiÛi`ÊLi>À}°







1/"
ÊÌÊÀiÕÃiÊÀiÛi`ÊLi>À}°




£ä®Ê Ã>ÃÃiLÞÊvÊ*À«iiÀÊ->vÌÊÕÃ}
ÜiÀÊ1Ì
/

£Î{Ó
/

£Î{Ó
/

£Î{Ó
/

£Î{Ó
/

£Î{Ó
,-
""
"
,-
""
"
"
'%!2'%!2
,
Ó°*>ÀÌÃÊ>ÞÕÌ
i>ÀÊ>Ãi
"
'%!2'%!2
,
,-
""
"
/

£Î{Ó
*ÉÊ}° £{
ÜiÀÊ1Ì
£°-«iV>Ê/Ã







4st 25/30 2016
%XAMPLE0RESSURE
#ONVENTIONALSYSTEMKILOGRAMMETERUNIT
#ONVENTIONALSYSTEM53POUNDINCHUNIT
3)UNITKGFCM

-0A
-EASUREMENTSARESHOWNUSING3)UNITFOLLOWEDBYCONVENTIONALUNITS53UNITAND;*APANESEDOMESTICUNIT=
-0APSI;KGFCM=
%XAMPLE4ORQUE

4HECONVENTIONALUNITFORMEASUREMENTOFFORCEUSESKGFKILOGRAMFORCETODISCRIMINATEITFROM
KGMASSKILOGRAMOF3)UNITSYSTEM
.qMLBqFT;KGFqM=
%XAMPLE6OLUME
CM

FLOZ
%XAMPLE,ENGTH
MMIN
This manual uses SI unit system (International System of Units) for pressure, force (load), torque and
stress. This manual newly adopts the international unit construction system (SI unit system) followed by the
conventional imperial and metric systems enclosed by ( ) and [ ] as described below.
<Reference>
What is the SI unit system?
Although the measurement unit is standardized mostly with metric system in the world, the metric system
includes different kinds of unit systems.
Though the metric system was established expecting that a single unit system would be used in the world,
various physical units were established later, resulting in branching the metric system in different unit
systems.
The new unit system is called "International System of Units" because it was established for the purpose of
unifying the different unit systems.
Since the metric system was initially established in France, and International Bureau of Weights and
Measures (IBWM) is located in Paris, General Conference of Weights and Measures (GCWM) passed a
resolution of the international unit system as "Systéme International d'Unités (French)" that is abbreviated as
"SI unit".
For example, conventional metric system uses the unit of mass (kg) and unit of force (kg or kgf) without
discriminating them, but the SI unit system uses, for example, "kg" as the unit of mass, and "N" as the unit of
force, aiming to apply a kind of unit for a kind of physical quantity.

ii 4st 25/30 2016
iÃVÀ«ÌÊvÊ*VÌ}À>«
-AINTENANCE
3ERVICE
)NFORMATION 3ERVICE$ATA
3PECIFIED
%LECTRICAL
6ALUE
STROKE
ENGINEOIL
!4&$%82/.III 'EAROIL
STROKE
ENGINEOIL
3CREW,OCKING
!GENT
;4HREE"OND¤=
s 
,UBRICATION
/IL
&UEL3YSTEM
&UEL)NJECTION
3PECIAL4OOL
3PECIFIED
-EASUREMENT
6ALUE
,OWER5NIT %LECTRICAL
3YSTEM
0OWER5NIT
4ROUBLESHOOTING
4IGHTENING
4ORQUE
!CCESSORIES 7IRING
$IAGRAMS
"RACKET
4HEFOLLOWINGSYMBOLSREPRESENTTHECONTENTSOFINDIVIDUALCHAPTERS
4HEFOLLOWINGSYMBOLSINDICATEITEMSNEEDEDFORTHESERVICE
4HEFOLLOWINGSYMBOLSINDICATEAPOINTTOWHICHLUBRICATIONOILSEALINGAGENTORSCREWLOCKINGAGENTISTOBEAPPLIED
3CREW,OCKING
!GENT
;4HREE"OND¤=
s "
/"-'REASE
4EFLON¤'REASE
4%&,/.
/IL#OMPOUND
; 3HIETSU3ILICON =
3/#
,OW
4EMPERATURE
,ITHIUM'REASE
,)4()5-
)NSULATING
'REASE
).3
;+ONISHI"OND=
s '
3EALING!GENT
;4HREE"OND¤=
s #
)NSTANT!DHESIVE
;4HREE"OND¤=
s
3CREW,OCKING
!GENT
;,OCTITE¤=
s 
3PECIFIED0ART
4EST2UN
!DJUSTMENT
%NGINE20-
5SE,IMIT
"
,*
" 
{ÃÌ
"
ÓÃÌ
"
/
/
"
/
,-
/
,-
£Ç
£Ç
" 
"
'%!2
'%!2



/



/
"

"
"
/

#
#
""*°

-"
-"
 -
,-


/
ÀÉ
,-
"
"

iii
4st 25/30 2016
£°-iÀÛViÊvÀ>Ì
£Ê `iÌvV>ÌÊ}iÊ-iÀ>Ê ÕLiÀ® ÊoÊ1-2
ÓÊ -iVÕÀ}ÊvÊÜÀÊÃ>viÌÞÊ ooooo 1-2
1) Fire Prevention …………………………… 1-2
2) Ventilation …………………………………… 1-2
3) Protection …………………………………… 1-2
4) Genuine Parts ……………………………… 1-2
5) Tools ………………………………………… 1-3
6) Recommendations on service …………… 1-3
7) Cautions in disassembling and assembling components … 1-4
ÎÊ /ÃÊ>`ÊÃÌÀÕiÌÃÊ oooooo Ê1-5
1) Test Propeller ……………………………… 1-5
2) Measuring instruments …………………… 1-5
3) Special Tools ……………………………… 1-6
{Ê *Ài`iÛiÀÞÊëiVÌÊ ooooo Ê1-9
1) Steering Handle …………………………… 1-9
2) Gear Shift …………………………………… 1-9
3) Engine Oil…………………………………… 1-9
4) Gear Oil……………………………………… 1-9
5) Fuel Line …………………………………… 1-10
6) Rigging ……………………………………… 1-10
7) Inspection of PTT unit……………………… 1-10
8) Inspection of gas shock absorber………… 1-10
9)
Inspection of starting switch andstop switch … 1-11
10) Cooling water check port ………………… 1-12
11) Idling ………………………………………… 1-12
12) Propeller Selection ………………………… 1-12
13) Trim Tab …………………………………… 1-13
xÊ Ài>Ê"«iÀ>ÌÊ oooooooo Ê1-13
ÈÊ /iÃÌÊ,ÕÊ oooooooooooooo Ê1-14
ÇÊ iVÃÊvÌiÀÊ/iÃÌÊ,ÕÊoooooo Ê1-14
Ó°-iÀÛViÊ>Ì>
£Ê "ÕÌiÊiÃÃÊoooooooo Ê2-2
1) Engine Dimensions………………………… 2-2
2) Transom Bolts ……………………………… 2-3
ÓÊ ÕiÊiVÌÊ-ÞÃÌiÊ oooooo Ê2-4
1) ECU Fuel Feed System …………………… 2-4
ÎÊ }iÊÕLÀV>ÌÊ-ÞÃÌiÊ>}À> ÊÊ2-5
{Ê }Ê7>ÌiÀÊ-ÞÃÌiÊ>}À>Ê Ê2-6
xÊ -«iVvV>ÌÃÊooooooooo Ê2-7
ÈÊ >Ìi>ViÊ>Ì>Êooooooo Ê2-10
ÇÊ /}Ìi}Ê/ÀµÕiÊ>Ì>Êoooo Ê2-18
nÊ -i>>ÌÊ««V>ÌÊV>ÌÃÊ Ê2-20
ΰ>Ìi>Vi
£Ê -«iV>Ê/ÃÊ ooooooooooo 3-2
ÓÊ ëiVÌÊ-Vi`ÕiÊ ooooooo 3-3
ÎÊ ëiVÌÊÌiÃÊ ooooooooo 3-4
1) Inspection of Top Cowl …………………… 3-4
2) Inspection of Fuel System Piping ………… 3-4
3) Inspection of Fuel Tank …………………… 3-5
4) Inspection of Fuel Filter …………………… 3-5
5) Replacement of Engine Oil ……………… 3-6
6) Replacement of Oil Filter ………………… 3-7
7) Inspection of Gear Oil Quantity…………… 3-8
8) Inspection of Water Pump …………… 3-8
9) Replacement of Gear Oil …………… 3-10
10) Inspection of Gear Case (for leakage) 3-11
11) Inspection of Timing Belt …………… 3-12
12) Replacement of Timing Belt ………… 3-13
13) Installation of Timing Belt …………… 3-15
14) Inspection of Spark Plugs …………… 3-17
15) Inspection of Compression Pressure 3-18
16)
Inspection and Adjustment of Valve Clearance 3-19
17) Throttle Cable ………………………… 3-20
18) Inspection of Shift Lever Gear Operations … 3-24
19) Inspection of PTT Unit Operation …… 3-25
20)
Inspection of Gas Assistant Unit Operations 3-25
21) Inspection of PTT Fluid Quantity …… 3-26
22) Inspection of Idle Speed……………… 3-27
23) Inspection of Ignition Timing ………… 3-27
24) Inspection of Anodes ………………… 3-28
25) Replacement of Anodes ……………… 3-28
26) Inspection of Propeller ……………… 3-29
27) Inspection of Thermostat …………… 3-29
28) Inspection of Cooling Water Passage … 3-30
29) Flushing with Water…………………… 3-31
30) Inspection of Battery ………………… 3-32
31) Greasing Points ……………………… 3-33
{° ÕiÊ-ÞÃÌiÊÕiÊiVÌ®
£Ê -«iV>Ê/ÃÊoooooooooo Ê4-2
ÓÊ *«}ÊÀÀ>}iiÌÊ>}À>ÊÊ4-3
Ê
Fuel Hose, Vent Hose, Breather Hose, Cooling Water Hose … 4-3
ÎÊ *>ÀÌÃÊ>ÞÕÌÊoooooooooo Ê4-4
Fuel System ……………………………… 4-4
Intake Manifold …………………………… 4-6
Magneto …………………………………… 4-8
Electric Parts ……………………………… 4-9
Separate Fuel Tank ……………………… 4-11
{Ê 1Ê-ÞÃÌiÊ oooooooooo Ê4-12
Ê £®Ê v}ÕÀ>ÌÊvÊ1Ê-ÞÃÌi ÊÊ4-12
1) Sensors ………………………………… 4-13
2) Actuators ……………………………… 4-15
3) Control System (ECU) ……………… 4-16
Ê Ó®Ê ÌÀÊ-ÞÃÌiÊ ooooooo Ê4-16
Ê Î®Ê ÕiÊiVÌÊÌÀÊoooo Ê4-17
1) Fuel Injection Timing ………………… 4-17
2) Starting Fuel Increase Correction …… 4-18
3)
Acceleration Fuel Increase Correction 4-18
4) Deceleration Fuel Decrease Correction 4-18
5) Correction Based On Intake Air Temperature … 4-18
6) Correction Based On Cylinder Cooling Water Temperature 4-18
Ê {®Ê ÌÀÊvÊÕiÊii`Ê*Õ«Ê*®Ê Ê4-18
Ê x®Ê ÌÀÊvÊ/>ViÌiÀÊ ooo Ê4-18
Ê È®Ê 7>À}ÊÕââiÀÊ>`Ê>«Ê®]Ê>`Ê
ÊÊ ÌÀÊvÊ}iÊ,iÛÕÌÊ-«ii` ÊÊ4-19
1)
Locations of warning buzzer and lamp (LED) … 4-19
2)
Warning notification, abnormality and action to be taken 4-19

iv 4st 25/30 2016
xÊ }ÌÊ-ÞÃÌiÊ oooooooooo Ê4-20
Ê £®Ê v}ÕÀ>ÌÊvÊ}ÌÊ-ÞÃÌi Êoo Ê4-20
Ó®Ê }ÌÊÌÀÊ oooooooo Ê4-21
1) Ignition Timing Controls …………………… 4-21
2) Ignition and Combustion Orders ………… 4-21
3) Ignition Timing ……………………………… 4-21
4) Operations ………………………………… 4-21
ÊÎ®Ê ÕiÊii`Ê-ÞÃÌiÊ ooooooo Ê4-22
ÈÊ «iÌÃÊvÊÕiÊii`Ê-ÞÃÌi ÊooÊ4-23
1)
Fuel Pump (Low Pressure Mechanical Pump) …… 4-23
2) Vapor Separator …………………………… 4-23
3) Fuel Regulator ……………………………… 4-24
4) Fuel Cooler ………………………………… 4-24
ÇÊ "ÕÌiÊvÊÕiÊiVÌÊ-ÞÃÌi Êooo Ê4-25
1) Air Intake System ………………………… 4-25
nÊ ëiVÌÊÌiÃÊ ooooooooo Ê4-26
1)
Inspection of Fuel Supply System Piping …… 4-26
2) Inspection of Filter ………………………… 4-26
3) Inspection of Fuel Pump ………………… 4-28
4) Inspection of Fuel Connector …………… 4-28
5) Measuring fuel pressure ………………… 4-29
6) Inspection of Fuel Regulator ……………… 4-30
7) Draining Fuel ……………………………… 4-31
8) Disassembly of Vapor Separator ………… 4-31
9) Inspection of Vapor Separator …………… 4-32
10) Reassembly of Vapor Separator ………… 4-33
11) Inspection of ISC (Idle Speed Control) ……… 4-33
12) Inspection of Idle Speed ………………… 4-33
x°*ÜiÀÊ1Ì
£Ê -«iV>Ê/ÃÊ ooooooooooo Ê5-2
ÓÊ *>ÀÌÃÊ>ÞÕÌÊoooooooooooo Ê5-3
Engine…………………………………………… 5-3
Recoil Starter…………………………………… 5-4
Magneto ………………………………………… 5-5
Electric Parts …………………………………… 5-6
Fuel System …………………………………… 5-8
Intake Manifold ………………………………… 5-10
Pully • Timing belt ……………………………… 5-12
Cylinder head • Oil pump……………………… 5-13
Cylinder • Crank case ………………………… 5-15
Piston • Crankshaft …………………………… 5-16
Top Cowl………………………………………… 5-17
ÎÊ ëiVÌÊÌiÃÊ ooooooooo Ê5-18
1) Inspection of Compression Pressure …… 5-18
2) Inspection of Oil Pressure ………………… 5-19
3) Inspection of Valve Clearance …………… 5-20
4) Removing Power Unit……………………… 5-21
5) Removing Timing Belt and Pulley………… 5-24
6) Inspection of Timing Belt ………………… 5-25
7) Installation of Pulley and Timing Belt …… 5-26
8) Removing Cylinder Head ………………… 5-29
9) Inspection of Valve Spring ………………… 5-31
10) Inspection of Valve ………………………… 5-32
11) Inspection of Valve Guide ………………… 5-32
12) Inspection of Valve Seat…………………… 5-33
13) Correction of Valve Seat ………………… 5-34
14) Inspection of Rocker Arm and Rocker Arm Shaft …… 5-36
15) Inspection of Cam Shaft ……………… 5-37
16) Inspection of Cylinder Head ………… 5-38
17) Inspection of Oil Pump ……………… 5-39
18) Installation of Valves ………………… 5-40
19) Installation of Cam Shaft …………… 5-41
20) Installation of Rocker Arm Shaft …… 5-41
21) Installation of Oil Pump ……………… 5-42
22) Installation of Cylinder Head ………… 5-43
23) Disassembly of Cylinder Block ……… 5-44
24) Inspection of Piston Outer Diameter 5-45
25) Inspection of Cylinder Inner Diameter 5-45
26) Inspection of Piston Clearance ……… 5-45
27)
Inspection of Piston Ring Side Clearance 5-46
28) Inspection of Piston Rings …………… 5-46
29) Inspection of Piston Pins …………… 5-47
30) Inspection of Connecting Rod Small End Inner Diameter 5-47
31) Inspection of Connecting Rod Big End Side Clearance … 5-47
32) Inspection of Crankshaft……………… 5-48
33) Inspection of Crank Pin Oil Clearance 5-49
34) Inspection of Crankshaft Main Journal Oil Clearance 5-50
35) Inner Diameter of Cylinder/Crank Case Bearing Holder (Inner Diameter Code) 5-51
36) Thickness of Bearing (Color of Inner Diameter Code) 5-51
37) Assembling Piston and Connecting Rod 5-52
38) Installation of Power Unit …………… 5-56
39) Removing Recoil Starter …………… 5-58
40) Disassembly of Recoil Starter ……… 5-58
41) Inspection of Recoil Starter ………… 5-59
42) Installation of Recoil Starter ………… 5-60
È°ÜiÀÊ1Ì
£Ê -«iV>Ê/ÃÊoooooooooo Ê6-2
ÓÊ *>ÀÌÃÊ>ÞÕÌÊoooooooooo Ê6-4
Gear Case ………………………………… 6-4
Drive System & Water Pump …………… 6-5
Shift ………………………………………… 6-7
ÎÊ ëiVÌÊÌiÃÊ ooooooo Ê6-8
1) Draining Gear Oil……………………… 6-8
2) Removing Propeller…………………… 6-8
3) Removing Lower Unit ………………… 6-9
4) Disassembly of Water Pump ………… 6-9
5) Inspection of Water Pump …………… 6-10
6)
Removing Propeller Shaft Housing Ass'y 6-10
7) Disassembly of Propeller Shaft Ass'y 6-11
8) Inspection of Propeller Shaft ………… 6-11
9) Assembly of Propeller Shaft Ass'y … 6-11
10) Disassembly of Propeller Shaft Housing 6-12
11) Inspection of Propeller Shaft Housing 6-13
12) Assembly of Propeller Shaft Housing 6-14
13) Removing Pump Case (Lower) ……… 6-15
14) Disassembly of Pump Case (Lower) 6-15
15) Assembly of Pump Case (Lower) …… 6-15
16) Removing Clutch Cam and Cam Rod 6-15
17) Disassembly of Clutch Cam and Cam Rod 6-15
18) Inspection of Cam Rod and Clutch Cam 6-16
19) Assembly of Cam Rod and Clutch Cam 6-16

v
4st 25/30 2016
20) Removing Drive Shaft …………………… 6-16
21) Disassembly of Drive Shaft ……………… 6-16
22) Inspection of Drive Shaft ………………… 6-17
23) Disassembly of Forward Gear (A Gear) … 6-17
24)
Inspection of Pinion Gear (B Gear)and Forward Gear (A Gear) 6-17
25) Assembly of Forward Gear (A Gear) …… 6-17
26) Assembly of Drive Shaft…………………… 6-18
27) Disassembly of Gear Case ……………… 6-18
28) Inspection of Gear Case ………………… 6-20
29) Assembly of Lower Unit …………………… 6-20
30) Installation of Pinion Gear (B Gear) ……… 6-22
31) Setting Pinion Gear (B Gear) Height …… 6-23
32) Setting Forward Gear (A Gear) Backlash … 6-25
33) Reassembly of Pinion Gear Nut (B Gear Nut) 6-27
34) Assembly of Propeller Shaft Housing …… 6-27
35) Reassembly of Pump Case (Lower) …… 6-28
36) Assembly of Water Pump ………………… 6-28
37) Installation of Lower Unit ………………… 6-30
Ç°À>ViÌ
£Ê -«iV>Ê/ÃÊ ooooooooooo Ê7-2
ÓÊ *//Ê7À}Ê>`Ê>ÞÕÌÊ>}À>ÊÊ7-3
ÎÊ *>ÀÌÃÊ>ÞÕÌÊoooooooooooo Ê7-4
Drive Shaft Housing …………………………… 7-4
Swivel Bracket (Mechanical Tilt) ……………… 7-5
Bracket (PTT • Gas Assistant)………………… 7-8
Power Tilt ……………………………………… 7-10
Bottom Cowl …………………………………… 7-12
Shift • Throttle ………………………………… 7-14
{Ê ëiVÌÊÌiÃÊ ooooooooo Ê7-15
1) Inspection of Throttle Cable ……………… 7-15
2) Installation of Tiller Handle ………………… 7-15
3) Adjustment of Co-pilot Plate ……………… 7-17
4) Removing Drive Shaft Housing …………… 7-17
5) Pulling Out Upper Mount ………………… 7-18
6) Disassembly of Drive Shaft Housing …… 7-19
7) Inspection of Oil Strainer ………………… 7-19
8) Assembly of Drive Shaft Housing ………… 7-19
9) Installation of Drive Shaft Housing Ass'y … 7-21
10) Removing Steering Shaft ………………… 7-21
11) Installing Steering Shaft …………………… 7-22
12)
Removing Clamp Bracket (PTT or Gas Assistant Model) 7-23
13) Removing Clamp Bracket (Mechanical Tilt Model) …… 7-23
14) Installation of Clamp Bracket (PTT or Gas Assistant Model) 7-24
15) Installation of Clamp Bracket (Mechanical Tilt Model) … 7-24
16) Removing PTT Unit/Gas Shock Absorber 7-25
17) Removing PTT Motor ……………………… 7-26
18) Removing PTT Pump and Valves ………… 7-26
19) Inspection of PTT Pump and Valves …… 7-26
20) Removing Tilt Cylinder…………………… 7-27
21) Inspection of Tilt Cylinder ……………… 7-27
22) Inspection of Valve ……………………… 7-28
23) Installation of PTT Pump and Motor …… 7-28
24) Assembly of Tilt Cylinder ………………… 7-29
25)
Air-Purging PTT Unit (separated from outboard motor) 7-31
26) Installation of PTT Unit/Gas Shock Absorber ……… 7-33
27) Air-Purging PTT Unit (installed on the outboard motor) 7-34
28) Inspection of PTT Solenoid……………… 7-35
29) Inspection of PTT Switch………………… 7-36
n°iVÌÀV>Ê-ÞÃÌi
£Ê -«iV>Ê/ÃÊoooooooooo Ê8-2
ÓÊ iVÌÀV>Ê«iÌÊ>ÞÕÌÊÊ8-3
Port Side View …………………………… 8-3
Bow Side View …………………………… 8-4
Starboard Side View……………………… 8-5
Top View …………………………………… 8-6
Tiller Handle Model ……………………… 8-7
ÎÊ *>ÀÌÃÊ>ÞÕÌÊoooooooooo Ê8-8
Magneto …………………………………… 8-8
Electric Parts ……………………………… 8-9
Fuel System ……………………………… 8-11
{Ê
}ÌÊ-ÞÃÌi]Ê}ÌÊÌÀÊ-ÞÃÌi ÊÊ8-13
1) Inspection of Ignition Sparks ………… 8-13
2) Inspection of Plug Cap ……………… 8-13
3) Inspection of Ignition Coils …………… 8-14
4) Inspection of Alternator ……………… 8-14
5) Inspection of Pulser Coil……………… 8-15
6) Inspection of Oil Pressure Switch …… 8-15
7) Inspection of Water Temperature Sensor 8-16
8) Inspection of Neutral Switch (Tiller Handle Model) 8-16
9) Inspection of Start Switch (Tiller Handle Model) … 8-16
10) Inspection of Stop Switch …………… 8-17
xÊ ÕiÊÌÀÊ-ÞÃÌiÊ ooooo Ê8-18
1) Inspection of Injectors………………… 8-18
2) Inspection of ISC Valve ……………… 8-18
3)
Inspection of MAT (Manifold Temperature) Sensor … 8-19
4) Inspection of Fuel Feed Pump (FFP) 8-19
5) Inspection of Throttle Position Sensor 8-19
ÈÊ -Ì>ÀÌ}Ê-ÞÃÌiÊoooooooo Ê8-20
1) Inspection of Fuse …………………… 8-20
2) Inspection of Starter Solenoid ……… 8-20
3) Disassembly of Starter Motor ……… 8-20
4) Inspection of Starter Motor Pinion … 8-21
5) Inspection of Armature ……………… 8-21

vi 4st 25/30 2016
6) Inspection of Brushes……………………… 8-22
7) Inspection of Starter Motor Operation …… 8-22
ÇÊ >ÌÌiÀÞÊ>À}}Ê-ÞÃÌiÊ oooo Ê8-23
1) Inspection of Alternator …………………… 8-23
2) Inspection of Rectifier……………………… 8-23
nÊ 1ÊÕ«iÀÊoooooooooooo Ê8-24
°/ÀÕLiÃÌ}
£Ê /ÀÕLiÃÌ}ÊÃÌÊ ooooooo Ê9-2
ÓÊ *ÜiÀÊ1ÌÊooooooooooooo Ê9-3
State 1 : Engine will not start or is a little hard to start. 9-3
Starting System……………………………… 9-3
Ignition System ……………………………… 9-5
Fuel System ………………………………… 9-7
State 2 : Full throttle engine revolution speed is low.
Engine revolution speed fall off.Engine stalls … 9-9
Ignition System ……………………………… 9-10
Fuel System ………………………………… 9-11
Lubrication System ………………………… 9-12
Cooling System……………………………… 9-13
State 3 : Engine rotation is unstable or hunting occurs
in low speed range. ……………………… 9-14
Ignition System ……………………………… 9-15
Fuel System ………………………………… 9-16
ÎÊ *//Ê1ÌÊ oooooooooooooo 9-17
State 1 : PTT will not operate. ………………… 9-17
State 2 : PTT is not capable of sustaining outboard motor. 9-18
{Ê >}ÃÃÊ ooooooooooo Ê9-19
1.Set Up ………………………………………… 9-19
1) Diagnosis Software Install ……………… 9-20
2) Installing USB to serial converter
driver (If there is no RS232 port) ……… 9-21
2.Hardware Connection …………………… 9-22
1) Preparation ……………………………… 9-22
2) Position of ON/OFF switch for function test
 and running (drop) test …………………… 9-23
3.Operating Procedure ……………………… 9-24
1) Start Up …………………………………… 9-24
2) Models and Menu Selection …………… 9-24
3) Preface and Introducion ………………… 9-24
4) Setting Communication (COM) Port …… 9-25
5) Engine Monitor …………………………… 9-27
6) Diagnostic History ……………………… 9-28
7) At Engine Shut-down Test ……………… 9-29
8) At Engine Running Test ………………… 9-30
9) Explanation of Error code ……………… 9-31
10) Exit Diagnostic ………………………… 9-31
£ä°VViÃÃÀiÃ
£Ê ,iÌiÊÌÀÊ«iÌÃÊo Ê10-2
1)
Installation of Remote Control Cable (Engine Side)
Remote Control Model ……………………… 10-2
ÓÊ ÃÌ>>ÌÊvÊiÌiÀÃÊ>`Ê>ÌÌiÀÞ ÊÊ10-5
1) Installation of Meters ………………… 10-5
2) Installation of Battery ………………… 10-5
3)
Wiring Diagram of Remote and Control Meters 10-6
ÎÊ "«iÀ>ÌÊoooooooooooo Ê10-7
1) Warning Indication …………………… 10-7
££°7À}Ê>}À>
7À}Ê>ÀÌÊooooooooooo Ê11-2
ÉÊ>}ÊiÌiÀ®Êooooo Ê11-3
ÉÉ/Ê>}ÊiÌiÀ®Êooo Ê11-5
ÉÊ}Ì>ÊiÌiÀ®Ê ooooo Ê11-7
ÉÉ/Ê}Ì>ÊiÌiÀ®Ê ooo Ê11-9
É/Ê>}ÊiÌiÀ®Ê ooooo Ê11-11
É*É*/Ê>}ÊiÌiÀ®Êooo Ê11-13
É/Ê}Ì>ÊiÌiÀ®Ê ooooo Ê11-15
*É*/Ê}Ì>ÊiÌiÀ®Ê ooooo Ê11-17

vii
4st 25/30 2016
Ê£Ê-iÀÛViÊvÀ>Ì
ÊÓÊ -iÀÛViÊ>Ì>
ÊÎÊ >Ìi>Vi
Ê{Ê
ÕiÊ-ÞÃÌiÊÕiÊiVÌ®
ÊxÊ *ÜiÀÊ1Ì
ÊÈÊ ÜiÀÊ1Ì
ÊÇÊ À>ViÌ
ÊnÊ iVÌÀV>Ê-ÞÃÌi
ÊÊ /ÀÕLiÃÌ}
Ê
£äÊ VViÃÃÀiÃ
££ÊÊ 7À}Ê>}À>
 8
" 
ÀÉ

viii 4st 25/30 2016

£
-iÀÛViÊvÀ>Ì

£Ê `iÌvV>ÌÊ}iÊ-iÀ>Ê ÕLiÀ® Êoo Ê1-2
ÓÊ -iVÕÀ}ÊvÊÜÀÊÃ>viÌÞÊ ooooo Ê1-2
1) Fire Prevention …………………………… 1-2
2) Ventilation …………………………………… 1-2
3) Protection …………………………………… 1-2
4) Genuine Parts ……………………………… 1-2
5) Tools ………………………………………… 1-3
6) Recommendations on service …………… 1-3
7) Cautions in disassembling and
assembling components ………………… 1-4
ÎÊ /ÃÊ>`ÊÃÌÀÕiÌÃÊ oooooo Ê1-5
1) Test Propeller ……………………………… 1-5
2) Measuring instruments …………………… 1-5
3) Special Tools ……………………………… 1-6
{Ê *Ài`iÛiÀÞÊëiVÌÊ ooooo Ê1-9
1) Steering Handle …………………………… 1-9
2) Gear Shift ……………………………… 1-9
3) Engine Oil ……………………………… 1-9
4) Gear Oil………………………………… 1-9
5) Fuel Line ……………………………… 1-10
6) Rigging ………………………………… 1-10
7) Inspection of PTT unit………………… 1-10
8) Inspection of gas shock absorber …… 1-10
9) Inspection of starting switch and
stop switch …………………………… 1-11
10) Cooling water check port …………… 1-12
11) Idling …………………………………… 1-12
12) Propeller Selection …………………… 1-12
13) Trim Tab ……………………………… 1-13
xÊ Ài>Ê"«iÀ>ÌÊ oooooo Ê1-13
ÈÊ /iÃÌÊ,ÕÊ oooooooooooo Ê1-14
ÇÊ iVÃÊvÌiÀÊ/iÃÌÊ,ÕÊ oooo Ê1-14

1-2
-iÀÛViÊvÀ>Ì
4st 25/30 2016
£°Ê `iÌvV>ÌÊ}iÊ-iÀ>Ê ÕLiÀ®
Engine serial number is stamped on the bottom cowl of
outboard motor body.
Ó°Ê-iVÕÀ}ÊvÊÜÀÊÃ>viÌÞ
£®ÊÀiÊ*ÀiÛiÌ
Gasoline is hazardous material and very flammable. Do not
handle gasoline near ignition source such as spark or static
electricity.
Ó®Ê6iÌ>Ì
Exhaust gas or gasoline vapor is hazardous for human
health. Be sure to ventilate well when working indoors.
ήÊ*ÀÌiVÌ
Wear a pair of goggles, working gloves and safety shoes to
protect human body from chemicals and oils and eyes from
particles generated by grinding or polishing works. Avoid
adhesion of matters such as oil, grease or sealing agent to
the skin. In case of exposure to such matters, wash away
with soap or warm water immediately.
{®ÊiÕiÊ*>ÀÌÃ
Use parts and/or chemicals that are genuine items or
recommended.

'$)% %"#
&&  
%!$ 


('$%$'$%
Model Name
Model Type
Serial Number

4st 25/30 2016

x®Ê/Ã
Use specified special tools to prevent damaging to parts
and to perform work safely and surely. Be sure to follow
installation procedures described in this manual and use
tightening torque specified.
È®Ê,iVi`>ÌÃÊÊÃiÀÛVi
Remove foreign substances and dirt from outboard motor
body and individual parts by cleaning. Apply recommended
oil or grease to rotating areas and sliding surfaces. After
individual works, always perform verifications such as
ensuring smooth movement and sealing.
1-3
2
!#

1-4
-iÀÛViÊvÀ>Ì
4st 25/30 2016
/
,-
/



MMTOTHICKORMOREWOODED
0OWER5NIT7ORK"OARD
MMTOMMHOLE
Ç®Ê>ÕÌÃÊÊ`Ã>ÃÃiL}Ê>`Ê
Ê >ÃÃiL}ÊV«iÌÃ
(1) Secure outboard motor to dedicated stand firmly.
(2) Take special care not to scratch painted surface or mating
surfaces of cylinder and crankcase.
(3) Replace unreusable parts such as packings, gaskets, O
rings, oil seals, spring pins or split pins with new ones after
they were removed . Replace deformed snap rings with new
ones.
(4) When replacing parts, be sure to use genuine parts. For
fluids such as gear oil, use genuine product.
(5) Be sure to use special tools that are specified, and perform
the works properly.
(6) When reassembling parts, use their mating marks. For parts
without mating marks, simple marking makes reassembling
easier. Use applicable parts list for reference.
(7) Clean individual parts that have been removed, and check
their conditions.
(8) When reassembling parts, take sufficient care also for
details such as fits, repair limits, air tight, clogging of oil
holes for lubrication and greasing, packings, wirings and
piping. For components using many bolts and nuts for
assembling, such as cylinder head and crankcase, tighten
all the fasteners evenly to their specified torques clockwise
in two or three stages, inner ones first and then outer ones.
(Reverse the order when disassembling.)
(9) When installing bearings, face the flat (numbered) side to
the special assembling tool.
(10) When installing oil seals, be careful not to scratch the
surface of the lip that contacts with the shaft, and install
them in correct orientation. Apply recommended grease to
the lip before installation.
(11) When applying liquid packing, take sufficient care for the
thickness and quantity. Excessive application may be oozed
out, adversely affecting interior of the crankcase. Use
adhesive after thoroughly reading the instructions.
(12) When servicing power unit, use of wooden work board
makes the work easier.
)NTAKE3ILENCER












1-5

4st 25/30 2016
Ó®Êi>ÃÕÀ}ÊÃÌÀÕiÌÃ
For the following measuring instruments, use commercially available ones.
Circuit tester ( Resistance : 1Ω, 10Ω, 10 kΩ, AC voltage : 30 to 300V, DC voltage : 30V )
Vernier calipers ( M1 type, 300 mm )
Micrometer ( minimum graduation of 0.01, outer, 0 to 25 mm, 25 to 50 mm, 50 to 75 mm )
Cylinder gauge ( 4 to 6 mm, 10 to 25 mm, 25 to 30 mm, 50 to 75 mm )
Ring gauge ( ø5.5, ø16, ø25, ø30, ø61 )
Dial gauge ( minimum graduation of 0.01 )
Thickness gauge ( 0.03 to 0.3 mm )
V block
Surface plate ( 500 mm x 500 mm )
Dial gauge magnet base or dial gauge stand
Outboard motor model Rotational speed at WOT
(Wide Open Throttle) (r/min)
MFS 25 C approximately 5,200
MFS 30 C approximately 5,700
ΰÊ/ÃÊ>`ÊÃÌÀÕiÌÃ
£®Ê/iÃÌÊ*À«iiÀ
P/N. 3R0-64110-0
Outer diameter : 223mm
With : 11.5mm

1-6
-iÀÛViÊvÀ>Ì
4st 25/30 2016
ήÊ-«iV>Ê/Ã
Measuring gaps
Thickness Gauge
P/N. 353-72251-0
Removing/installing Pinion Nut (B Gear Nut)
Bevel Gear B Nut Wrench
P/N. 346-72231-0
Bevel Gear B Nut Socket
P/N. 346-72232-0
Installing forward gear
(A gear) bearing
Bevel Gear Bearing Installation Tool
P/N. 346-72719-0
Removing spring pin
Spring Pin Tool A
P/N. 345-72227-0
Installing spring pin
Spring Pin Tool B
P/N. 345-72228-0
Bevel Gear Bearing Puller Ass'y
P/N. 3A3-72755-0
Removing forward gear
(A gear) bearing outer race
Mount Puller Kit
P/N. 3AC-72760-0
Removing upper mount
Adjusting valve clearance
Torque Wrench
P/N. 3AC-99070-0
Measuring engine revolution
speed
Tachometer
P/N. 3AC-99010-0
Piston Slider
P/N. 3AC-72871-0

!
#








Installing piston
Adjusting valve clearance
Valve Clearance Driver
P/N. 3AC-99071-0
Compression Gauge
P/N. 3AC-99030-0
Measuring compression
pressure
Slide Hammer Kit
P/N. 3AC-99080-0
Removing forward gear
(A gear) bearing outer race
Inspecting pressure
Vacuum/Pressure Gauge
P/N. 3AC-99020-1

1-7

4st 25/30 2016
Installing/attaching drive shaft housing roller bearing
Roller bearing press Ass'y
P/N. 3AC-72900-1
&
&
Roller Bearing Attachment
P/N. 3AC-99710-0
Used with driver rod and center plate
Installing propeller shaft housing roller bearing
Oil Filter Wrench
P/N. 3AC-99090-0
Removing/installing oil filter Measuring pinion gear
(B gear) height
Shimming Gauge
P/N. 346-72250-0
Driver Rod
P/N. 3AC-99702-0
Used with center plate and
roller bearing attachment
Universal Puller Plate
P/N. 3AC-99750-0
Removing reverse gear/
bearing
Installing oil seal
Oil Seal Attachment
P/N. 3AC-99820-0
Used with driver rod Attaching
reverse gear (C gear) bearing
Bearing attachment
P/N. 3AC-99905-0
Oil Seal Attachment 3
P/N. 3AG-99820-0
Installing pump case (lower)
oil seal
Used with driver rod Installing oil
seal in the propeller shaft housing
Oil Seal Attachment 2
P/N. 3AD-99820-0
Removing/installing flywheel
Flywheel Puller Kit
P/N. 369-72211-0
Measuring backlash
Backlash Measuring Tool Clamp
P/N. 3B7-72720-0
Installing forward gear (A
gear) bearing outer race
Bearing Outer Press Kit
P/N. 3B7-72739-1

Measuring gap between forward and pinion gears
(A and B gears)
Backlash Measuring Tool Kit
P/N. 3C8-72234-0


 !

"
1-8
-iÀÛViÊvÀ>Ì
4st 25/30 2016
Inspecting sparks
Spark Tester
P/N. 3F3-72540-0
Crank Shaft Holder
P/N. 3R0-72815-0
2
Holding crank shaft
Measuring fuel pressure
Pressure Gauge Ass'y
P/N. 3T5-72880-0
Caulking clamp
Clamp Plier
P/N. 3T5-72864-0