Subaru EH72 FI Operating and installation instructions

ISSUE EMD-ES6790
2009.08
SERVICE INFORMATION
EH72  FI

CONTENTS
Section Title Page
1. SPECIFICATIONS .............................................................1
2. FEATURES .................................................................2
3. DESCRIPTION OF FUEL SYSTEM.................................................3
4. DISASSEMBLY AND REASSEMBLY ...............................................4
4-1PREPARATIONSANDSUGGESTIONS...............................................4
4-2SPECIALTOOLS.................................................................4
4-3DISASSEMBLYPROCEDURES(DIFFERENCE)........................................5
4-4 REASSEMBLY PROCEDURES (DIFFERENCE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
4-5BREAK-INOPERATION..........................................................14
5. DIAGRAM..................................................................15
6. THROTTLE BODY............................................................16
6-1SPECIFICATIONS...............................................................16
6-2FUNCTIONSANDCONSTRUCTION................................................16
6-3FUELSYSTEMOUTLINE.........................................................17
6-4FUELSYSTEMTESTINGANDDIAGNOSIS..........................................17
7. INSTALLATION..............................................................18
7-1INSTALLING ...................................................................18
7-2VENTILATION .................................................................18
7-3EXHAUSTGASDISCHARGE .....................................................18
7-4FUELSYSTEM .................................................................19
7-5 POWER TRANSMISSION TO DRIVEN MACHINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
8. TROUBLESHOOTING .........................................................20
8-1NOENGINEOPERATION.........................................................20
8-2STARTINGDIFFICULTIES........................................................21
8-3INSUFFICIENTOUTPUT .........................................................22
8-4OVERHEAT....................................................................22
8-5ROUGHIDLING.................................................................23
8-6HIGHENGINEOILCONSUMPTION ................................................23
8-7HIGHFUELCONSUMPTION......................................................24
8-8DETONATION..................................................................24
8-9ENGINEMISFIRE...............................................................25
8-10DIAGNOSISCODE.............................................................26
9. MAINTENANCE AND STORAGE .................................................28
9-1DAILYMAINTENANCE...........................................................28
9-2PERIODICMAINTENANCESCHEDULE.............................................28
9-3SPARKARRESTER(OPTIONAL)...................................................30
9-4ENGINESTORAGE..............................................................31
PREFACE
This manual covers the service information, trouble shooting procedures and so on of
EH72 FI (Fuel injection) engine.
Careful observance of the instructions given herein will result in better, safer and faster
service work.
For more detailed instructions of disassembling and reassembling procedures, please
refer to the service manual for EH63, 64, 65 and 72.

- 1 -
1. SPECIFICATIONS
Model EH72 FI
Type Air-Cooled, 4-Stroke, V-Twin Cylinder, Horizontal P.T.O. shaft,
OHV Gasoline Engine
Number of Cylinders - Bore × Stroke mm (in.)
2 - 84 ×65 (3.31 ×2.56)
Displacement ml (cu.in.) 720 (43.9)
Compression Ratio 8.1
Continuous Output kW(HP)/r.p.m. 14.9 (20.0) / 3600
Maximum Output kW(HP)/r.p.m.
Net : 17.9 (24.0) / 3600
Gross : 19.4 (26.1) / 3600
20.9 (28.0) / 4000
Maximum Torque N•m / r.p.m.
(kgf•m / r.p.m.)
(ft•lb. / r.p.m.)
52.2 / 2800
(5.32 / 2800)
(38.5 / 2800)
Direction of Rotation Counterclockwise as viewed from the P.T.O. shaft side
Cooling System Forced air cooling
Valve Arrangement Overhead Valve (OHV)
Lubrication Full pressure type with oil Cooler
Lubricant Automobile engine oil SAE #20, #30 or 10W-30;
Class SE or higher
Capacity of Lubricant L (U.S. gal.) 1.55 (0.41)
Throttle body Electronic Fuel injection
Fuel Automotive unleaded gasoline
Fuel Feed System Electronic Fuel pump
Ignition System Flywheel Magneto (Solid state)
Spark Plug BPR5ES(NGK) or BPR4EY(NGK)
Charging Capacity V - A 12 - 15 or 12 - 30 (Option)
Starting System Electric Starter
Governor System Centrifugal Flyweight type
Air cleaner Double Element type
Dry Weight kg (lb.)
with out muffler and control box 46 (101.3)
with STD muffler and control box 51.5 (113.4)
Dimensions
(L×W×H) mm (in.)
with out muffler and control box 317×477×480 (12.5×18.8×18.9)
with STD muffler and control box 464×499×480 (18.3×19.6×18.9)
*Specifications are subject to change without notice.

- 2 -
2. FEATURES
EH72 FI has been developed as a high performance model equipped with the electronic fuel
injection system.
HIGHER POWER OUTPUT
has been achieved by increasing inlet air volume with larger venturi bore.
ENVIRONMENTALLY FRIENDLY
By optimizing the fuel injection management, EH72 FI has achieved approx. 11% improvement
on the fuel efficiency, as well as drastic reduction on the exhaust emission.
Therefore, EH72 FI comply with CARB Tier 3 Emission Regulations in the USA.
COMPACT DESIGN
By adopting the Engine Control Unit (ECU) incorporated inside the throttle body of electronic fuel
injection system, EH72 FI has achieved very compact design, which is same envelope size as
carbureted engine, to keep superb mountability for machineries.
USER FRIENDLY
- Excellent startability
The newly developed electronic fuel injection system provides optimum fuel flow by sensing
ambient temperature.
It realizes easy and surefire start-up performance with no choke operation, even in the low-
temperature.
- Better response and acceleration
The electronic fuel injection system offers an excellent running performance which are less
subject to external circumstances, such as changes of ambient temperature and atmospheric
pressure. This means no need any manual adjustment at high altitude, such as changing main jet
of carburetor.

- 3 -
3. DESCRIPTION OF FUEL SYSTEM
This engine is equipped with Electronic Fuel
Injection system (FI system) integrated with
ECU (Engine Control Unit).
The FI system consists of throttle body
(2-barrel), ECU, MAP (Manifold Air Pressure)
sensor, injector, fuel pressure regulator,
temperature sensor, electric fuel pump, and
pulsation damper.
The fuel system is calibrated after careful testing for optimum all-round performance (including
starting, acceleration, fuel consumption, output power characteristics).
The throttle body monitors manifold air pressure and engine temperature at start up and performs
the choke function automatically.
While the engine is in operation, the throttle body monitors engine speed, manifold air pressure,
and engine temperature to ensure proper engine performance.
(For further information, refer to page 16, section “6 .THROTTLE BODY”.)
THROTTLE
BODY AY
INJECTOR
ECU
ECU (Engine Control Unit)
FUEL PRESSURE
REGULATOR
THROTTLE
BODY AY
CLEANER
ADAPTER
INTAKE
MANIFOLD
TEMPERATURE
SENSOR
PULSATION DAMPER
ELECTRIC
FUEL PUMP
OIL / FAIL
WARNING
LAMP
(OPTION)

- 4 -
4. DISASSEMBLY AND REASSEMBLY
4-1 PREPARATIONS AND SUGGESTIONS
When disassembling the engine, memorize the locations of individual parts so that they can be
reassembled correctly. If you are uncertain of identifying some parts, it is suggested that tags be
attached to them.
Have boxes ready to keep disassembled parts by group.
To prevent losing and misplacing, temporarily assemble each group of disassembled parts.
Carefully handle disassembled parts, and clean them with washing oil if necessary.
Use the correct tools in the correct way.
When disconnecting electric wirings, be sure to hold and disconnect the connector housing.
4-2 SPECIAL TOOLS
No Special Tool is needed for disassembling and reassembling the engine.
For pulling off the flywheel, universal type puller being popular in the market place as shown in
the illustration is needed.
Description Parts number
Flywheel puller for pulling off the flywheel
Flywheel puller with bolt
228-95001-17

- 5 -
4-3 DISASSEMBLY PROCEDURES (DIFFERENCE)
Step Parts to remove Remarks and procedures Parts Fasteners
8 Choke lever Choke lever not applicable.
9
Governor rod (1) Remove the governor rod spring from rod holder.
(2) Pick up the rod holder and remove the governor rod.
(See Fig.4-1)
(3) Remove the governor rod and the rod spring from
the governor lever.
(4) Loosen the bolt and remove the governor lever.
M6 bolt and washer : 1pc.
GOVERNOR ROD
ROD HOLDER
Turn the rod holder
clockwise to loosen.
VIEW A
Fig. 4-1
STEP 9
GOVERNOR SHAFT
GOVERNOR LEVER
ROD SPRING
GOVERNOR
ROD
ROD HOLDER
THROTTLE BODY
A
L
R

- 6 -
Step Parts to remove Remarks and procedures Parts Fasteners
10
Throttle body (1) Disconnect the two connectors from ECU under the
throttle body.
(2) Disconnect the two connectors from the two injectors
on the throttle body.
(3) Remove the nuts, adapter and throttle body from the
intake manifold.
M6 Flange nut : 4pcs.
STEP 10
CONNECTER
(ECU)
M6 FLANGE NUT
GOVERNOR LEVER
CONNECTER
(INJECTOR)
CONNECTER
(INJECTOR)
CLEANER
ADAPTER

- 7 -
Step Parts to remove Remarks and procedures Parts Fasteners
13
Fuel pump (1) Disconnect the connecter places from fuel pump wiring harness 2.
(2) Remove fuel pump ASSY and detach bracket.
M6 x 12 Flange bolt : 1 pc.
#1
IGNITION
COIL
STEP 13
STEP 14
PLUG
TERMINAL
M6 FLANGE BOLT
HOSE
CLAMP
HOSE
CLAMP
FUEL
PIPE
HOSE CLAMP
HOSE CLAMP
FUEL FILTER
FUEL PUMP
TO THROTTLE BODY
(ECU) and KEY SWITCH
M6 BOLT AND
WASHER ASSY
TO THROTTLE BODY
(ECU)
#2
IGNITION
COIL
PLUG TERMINAL
SPARK PLUG CAP
M6 BOLT AND
WASHER ASSY
CONNECTER
(FUEL PUMP)
SPARK
PLUG CAP
GROMMT
(PLUG CAP)
#2 CYLINDER
SIDE ONLY
#1 CYLINDER SIDE
#2 CYLINDER SIDE

- 8 -
Step Parts to remove Remarks and procedures Parts Fasteners
16
Regulator and Wire CP (1) Disconnect wire connector from regulator, and then
remove regulator from #1 cylinder baffle.
(2) Remove temperature sensor from main bearing cover.
(3) Disconnect the wiring harness 1.
(injector #1 / 2, temperature sensor, ignition coil #1 / 2)
(4) Disconnect the wiring harness 2
(fuel pump, ground, warning lamp, ignition coil ground)
M6 x 12 Flange bolt : 2 pcs.
Tapping screw : 1pc.
21 Spark plug Take care the spark plug is hot just after stopping engine. NGK : BPR5ES or BPR4EY
STEP 16
STEP 16
WIRING HARNESS
M6 FLANGE
BOLT REGULATOR
GASKET
INTAKE MANIFOLD
M8 FLANGE
NUT
GASKET
STEP 15
M8 FLANGE NUT
TO IGNITION COIL #1
TO IGNITION COIL #2
TO KEY
SWITCH
WHITE
CYLINDER
BAFFLE #1
TAPPING
SCREW
TEMPERATURE SENSOR
TO THROTTLE
BODY "L"SIDE
CONNECTER
(GRAY)
TO THROTTLE
BODY "R"SIDE
CONNECTER
(BLACK)
Blk(R)
(Blk)
Blk
Blk(Blk)
Blk(W)
Blk(Blk)
Blk(R)
R
(Blk)
Blk
Gry(Grn/R)
Blk(Blk)
Blk(Grn/R)
Blk(Blk/Blk)
Gry(Blk)
TEMPERATURE
SENSOR
INJECTOR #2
WIRING HARNESS 1
WIRING COLOR CODE
Blk : Black Gry : Gray R : Red Grn : Green W : Wite
( ) is inside wiring color code.
INJECTOR #1 WARNING
LAMP
IG COIL
GROUND
BATTERY
POWER
GROUND
FUEL PUMP
TO THROTTLE BODY
(ECU)
#1 CYLINDER SIDE
#2 CYLINDER SIDE
WIRING HARNESS 2

- 9 -
20) COOLING FAN
Attach cooling fan onto flywheel.
M6 x 16 bolt & washer : 4 pcs.
21) THROTTLE BODY
(1) Replace the gasket of manifold with a new
one and mount the throttle body on the
intake manifold.
(2) Replace the gasket of throttle body with a
new one and mount the cleaner adapter on
the throttle body.
M6 FLANGE NUT : 4pcs.
(3) Connect the connectors from ECU to the injectors.
M6 x 30 bolt & washer : 4pcs.
(2) Connect wiring from ECU to the primary
terminal of ignition coil.
(3) Clamp the wiring harness with wire bands
to the intake manifold.
22) IGNITION COIL and WIRE CP
(1) Temporally fit ignition coil to crankcase.
Adjust air gap between ignition coil and flywheel using a thickness gauge and tighten bolts.
4-4 REASSEMBLY PROCEDURES (DIFFERENCE)
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GASKET
INJECTOR
WIRING
HARNESS #1
WIRING
HARNESS #2
THROTTLE
BODY
INTAKE
MANIFOLD
CLEANER
ADAPTER
GASKET
7+,&.1(66*$8*( ,*1,7,21&2,/
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Tightening torque
6.8 - 8.8 N•m
(70 - 90 kgf•cm)
(5.1 - 6.5 ft•lb.)
Tightening torque
6.8 - 8.8 N•m
(70 - 90 kgf•cm)
(5.1 - 6.5 ft•lb.)
Tightening torque
6.8 - 8.8 N•m
(70 - 90 kgf•cm)
(5.1 - 6.5 ft•lb.)
Ignition coil air gap
0.3 - 0.5 mm
(0.012 - 0.020 in.)

- 10 -
23) GOVERNOR LEVER
Attach governor rod and rod spring
between governor lever and throttle body
throttle lever, and insert the governor lever
to governor lever shaft. Tighten locking bolt
temporarily.
24) SPEED CONTROL LEVER
(1) Install speed control bracket onto intake
manifold.
(2) Attach return spring, spacer, friction
washer, wing nut, etc. to speed control lever
as shown in the ilustration.
(3) Connect governor spring to governor lever
and speed control lever.
GOVERNOR
SHAFT
GOVERNOR
LEVER
ROD SPRING
GOVERNOR
ROD
ROD HOLDER
THROTTLE LEVER
A
L
R
ROD
SPRING
GOVERNOR ROD ROD HOLDER
Turn the rod holder
counter clockwise
and fix it.
Then hook the rod
spring as shown
on the diagram.
VIEW
A
STOP PLATE
SPRING WASHER
SPEED CONTROL
LEVER
M6 FLANGE
BOLT
M6 SELF LOCK
NUT
FRICTION
WASHER
FRICTION
WASHER
BRACKET UNIT,
speed control
E
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


D
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Fitting location of governor rod and governor spring
50 Hz 60 Hz
EH72 FI NA A-2(a)

- 11 -
25) ADJUST GOVERNOR SYSTEM
●Governor system is centrifugal flyweight
type. Governor weight is installed into
governor gear driven by crankshaft.
Governor weight movement is transferred
to throttle lever via governor shaft and
lever.
●Engine speed is maintained at the constant
speed by throttle valve opening and closing
operation in accordance with load condition
of engine.
(1) Push speed control lever all the way to the
high speed position and fix it by tightening
nut.
(2) Check that governor lever is pulled by
governor spring and throttle valve is fully
open.
(3) Turn governor shaft counterclockwise all
the way and tighten lock bolt to secure the
lever on the shaft.
26) BLOWER HOUSING
Attach blower housing to crankcase with
control box commonly fixed.
Connect fuel pipes onto blower housing.
BLOWER HOUSING(Front)
M6 x 14 Flange bolt : 4 pcs.
BLOWER HOUSING(Side)
M6 x 18 Flange bolt : 2 pcs.
M6 x 14 Flange bolt : 2 pcs.
GOVERNOR LEVER
GOVERNOR SHAFT
BLOWER
HOUSING
(Side)
Connect the wiring to
the electric starter.
BLOWER
HOUSING
(Front)
Tightening torque
3.9 - 5.9 N•m
(40 - 60 kgf•cm)
(2.9 - 4.3 ft•lb.)
Tightening torque
2.9 - 4.9 N•m
(30 - 50 kgf•cm)
(2.2 - 3.6 ft•lb.)

- 12 -
27) FUEL PUMP and FUEL PIPE
(1) Install fuel pump bracket onto #2 cylinder
baffle.
FUEL PUMP
M6 x 12 Flange bolt : 1 pc.
28) AIR CLEANER and BREATHER PIPE
(1) Connect breather pipe to air cleaner base.
(2) Fit air cleaner base onto throttle body.
M6 x 12 Flange bolt : 3 pcs.
(2) Connect the wiring to the fuel pump.
(3) Connect fuel pipe between throttle body
and fuel pump.
(2) Connect the wiring to the oil pressure
switch.
(3) Connect breather pipe to #1 cylinder head.
(4) Set air cleaner element along with urethane
foam onto base.
(5) Install air cleaner cover with knob.
29) OIL PRESSURE SWITCH
(1) Install oil pressure switch onto adapter (Oil
cooler).
FUEL FILTER
RETURN HOSE
PULSATION DAMPER
FUEL PUMP
CONNECTER
(FUEL PUMP)
AIR CLEANER BASE
2,/35(6685(6:,7&+
Tightening torque
6.8 - 8.8 N•m
(70 - 90 kgf•cm)
(5.0 - 6.5 ft•lb.)
Tightening torque
6.8 - 8.8 N•m
(70 - 90 kgf•cm)
(5.0 - 6.5 ft•lb.)
Tightening torque
5.9 - 9.8 N•m
(60 - 100 kgf•cm)
(4.3 - 7.2 ft•lb.)
NOTE ;
Not to tighten excessively.

- 13 -
31) MUFFLER
(1) Install Muffler bracket onto Cylinder head.
M8 x 20 bolt & washer : 2 pcs.
30) OIL FILTER
Apply oil to O-ring and install oil filter by
tightening about 3/4 turns after attaching
crankcase surface.
(2) Install Muffler onto Muffler bracket and
Cylinder head.
M8 SUS flange nut : 4 pcs.
(3) Install Muffler cover onto Muffler.
M6 Flange bolt : 6 pcs.
A
M6 FLANGE BOLT
A
MUFFLER
BLACKET
MUFFLER
COVER
M6 FLANGE
BOLT
M8 BOLT & WASHER
M6 FLANGE BOLT
GASKET
MUFFLER
M8 SUS
FLANGE NUT
O RING
OIL FILTER
3/4 TURNS
Tightening torque
16.6 - 18.6 N•m
(170 - 190 kgf•cm)
(12.3 - 13.7 ft•lb.)
Tightening torque
9.9 - 14.7 N•m
(100 - 150 kgf•cm)
(16.3 - 19.8 ft•lb.)
Tightening torque
16.6 - 18.6 N•m
(170 - 190 kgf•cm)
(12.3 - 13.7 ft•lb.)
Tightening torque
6.8 - 8.8 N•m
(70 - 90 kgf•cm)
(5.0 - 6.5 ft•lb.)
NOTE ;
Start engine after assembling,
and check for no oil leakage
from oil filter.

- 14 -
33) ENGINE OIL
Refill engine oil and start the engine.
Engine oil will be lubricated oil passages
and oil filter. Check the engine oil level and
refill again to the upper level of oil level
gauge.
32) FINAL CHECK
Be sure to check loosen bolts and nuts, and also electric wiring connections.
Oil Capacity
1.55 liter (0.41 U.S. gal.)
4-5 BREAK-IN OPERATION
An engine that has been completely overhauled by being fitted with a new piston, rings, valves
and connecting rod should be thoroughly RUN-IN before being put back into service. Good
bearing surfaces and running clearances between the various parts can only be established by
operating the engine under reduced speed and loads for a short period of time.
While the engine is being tested, check for oil leaks.
Make final carburetor adjustment and regulate the engine operating speed.
NOTE ;
* Check the oil level with the oil gauge inserted.
* Use “SE” (API classification) or higher grade
engine oil.
OIL GAUGE
UPPER LEVEL
LOWER LEVEL
OIL GAUGE
UPPER LEVEL
LOWER LEVEL
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Standard Option
STEP EH72 FI Engine speed (rpm) Time (minute)
1
No Load
2500 10
2 3000 10
3 3600 10
4 7.5kW (10.0HP) 3600 30
5 14.9kW (20.0HP) 3600 30

- 15 -
5. DIAGRAM
WIRING
SYSTEM BLOCK
THROTTLE
BODY
#1 CYLINDER SIDE
#2 CYLINDER SIDE
TEMPERATURE
SENSOR (MBC)
OIL
PRESSURE
SWITCH
ELECTRIC
FUEL PUMP
IGNITION
COIL #1
IGNITION
COIL #2 SPARK
PLUG
SPARK
PLUG
REGULATOR
BODY
CHARGE
COIL
ELECTRIC
STARTER
REGURATOR
OIL/FAIL WARNING LAMP
(OPTION)
BATTERY
12V
TACHO /
HOUR METER
(OPTION)
Grn
Blk : BLACK
W : WHITE
R : RED
Y : YELLOW
Grn : GREEN
Gry : GRAY
KEY SWITCH
(OPTION)
OFF
RUN
START
G M B L S
Blk
Blk
BlkBlk
Blk
Blk
(Covering: Blk)
Blk (Covering: Gry)
Blk Blk
Blk Grn
Blk
Blk
Blk
R
R
R
R
R
Blk / W
R
Y
Y
Y
W
W
W
Grn, R
(Covering: Blk)
(Wiring harness 2)
(Wiring harness 1)
Grn, R
(Covering: Gry)
Gry
Gry
L R
#1
CYLINDER
SIDE
#2
CYLINDER
SIDE
CLEANER
ADAPTER
12V-36AH
or larger
MAP SENSOR
MBC TEMPERATURE SENSOR
ECU : Engine Control Unit
MAP SENSOR : Manifold Air Pressure Sensor
ELECTRIC
FUEL
AIR PRESSURE
IG COIL #1 R.P.M
IG COIL #2 R.P.M
ECU
INJECTOR #1
INJECTOR #2
INTAKE BOOST
#1 CYL SIDE
KEY SW
BATTELY
RETURN
THROTTLE BODY
DELIVERY
FUEL FILTER
FUEL
REGULATOR
FUEL PUMP PULSATION
DAMPER
FUEL TANK

- 16 -
6. THROTTLE BODY
6-1 SPECIFICATIONS
This engine is equipped with Electronic Fuel Injection system (FI system) integrated with ECU
(Engine Control Unit).
The FI system consists of throttle body (2-barrel), ECU, MAP (Manifold Air Pressure) sensor,
injector, pressure regulator, temperature sensor, electric fuel pump, and pulsation damper.
The fuel system is calibrated after careful testing for optimum all-round performance (including
starting, acceleration, fuel consumption, output power characteristics).
The throttle body monitors air and engine temperature at start up and performs the choke
function automatically.
While the engine is in operation, the throttle body monitors engine speed, manifold air pressure,
and engine temperature to ensure proper engine performance.
6-2 FUNCTIONS AND CONSTRUCTION
6-2-1 ELECTRIC FUEL PUMP
The electric fuel pump is located below the throttle body, and actuated by power from the DC
battery. The fuel flows from the tank into the fuel pump. When the fuel pump is actuated by DC
battery, the fuel is pressurized by the pump and pushed into the throttle body pressure port.
6-2-2 FUEL PRESSURE REGULTOR
After the fuel pressure port is a diaphragm-type fuel pressure regulator.
The fuel pressure regulator relieves the throttle body of any excess fuel pressure and returns
excess fuel pressure back to the fuel tank through the fuel pressure return pipe.
6-2-3 FUEL INJECTOR
The throttle body pressure port feeds fuel at a regulated pressure to the fuel injectors.
Fuel is metered by the fuel injector that is actuated electronically by ECU.
The fuel is injected into the throttle bore and mixed with air from the air cleaner.
6-2-3 ENGINE CONTROL UNIT (ECU)
The ECU (engine control unit) on bottom of the throttle body is powered by DC battery. The
ECU monitors engine conditions such as engine speed, air pressure, and engine temperature.
With these inputs, the ECU actuates the fuel injector to ensure the fuel/air mixture is of optimum
concentration and is fed into the combustion chamber of the engine at the correct timing. When
engine speed reached to 4,200 rpm, the ECU cuts fuel to prevent over speed.
The ECU also controls the low oil sensor system and monitors voltage of DC battery, and each
wiring whether disconnecting or electrical short circuit.

- 17 -
6-2-4 WIRE HARNESS
The wire harness for the FI system connects key system components to the ECU.
The FI wire harness contains a temperature sensor that measures engine temperature, and
connects fuel injectors, ignition coils, electric fuel pump, pressure switch, and warning lamp.
The ECU uses this input to adjust to engine various conditions and monitors for failure diagnosis.
6-2-5 CHOKE SYSTEM
The throttle body monitors air pressure and engine temperature at start up and performs the
choke function automatically.
The choke system automatically adjusts for easier start of the engine in all weather conditions.
6-3 FUEL SYSTEM OUTLINE
6-4 FUEL SYSTEM TESTING AND DIAGNOSIS
Most fuel system malfunctions occur when the fuel/air ratio of the mixture is not correct.
This is usually caused by clogged fuel filters, air passages, fuel passages, or by variations in
the fuel level.
To get the best possible performance from the throttle body, make sure that the fuel feed and
air feed passages are free so air and fuel can flow freely through them.
The procedure for inspecting the fuel system is described below.
Run all system tests with a full tank of fresh, clean fuel.
Fuel Pressure Regulator
M.A.P. Sensor
Fuel Injector
ECU
Air
Cleaner
Magneto
Ignition
Unit
Ignition Pulse
Engine
Temperature
sensor
PULSATION
DAMPER
Fuel Tank
Throttle Body Assy
30kPa (0.3kgf/cm2)
Return
TANK
FUEL RETURN PIPE
FILTER PIPE FUEL
PUMP
FUEL
INJECTION COMBUSION
PULSATION
DAMPER
Fuel
Pump
Fuel
Filter
Muffler