Subaru EH72 LP-NG User Manual
EH72FI
SERVICE INFORMATION
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.
CONTENTS
Section Title Page
1. SPECIFICATIONS
2. FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
3. DESCRIPTION OF FUEL SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
4. DISASSEMBLY AND REASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
4-1 PREPARATIONS AND SUGGESTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
4-2 SPECIAL TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4-3 DISASSEMBLY PROCEDURES (DIFFERENCE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4-4 REASSEMBLY PROCEDURES (DIFFERENCE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
4-5 BREAK-IN OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
5. DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
6. THROTTLE BODY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
6-1 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
6-2 FUNCTIONS AND CONSTRUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
6-3 FUEL SYSTEM OUTLINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
6-4 FUEL SYSTEM TESTING AND DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
7. INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
7-1 INSTALLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
7-2 VENTILATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
7-3 EXHAUST GAS DISCHARGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
7-4 FUEL SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
7-5 POWER TRANSMISSION TO DRIVEN MACHINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
8. TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
8-1 NO ENGINE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
8-2 STARTING DIFFICULTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
8-3 INSUFFICIENT OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
8-4 OVERHEAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
8-5 ROUGH IDLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
8-6 HIGH ENGINE OIL CONSUMPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
8-7 HIGH FUEL CONSUMPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
8-8 DETONATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
8-9 ENGINE MISFIRE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
8-10 DIAGNOSIS CODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
9. MAINTENANCE AND STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
9-1 DAILY MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
9-2 PERIODIC MAINTENANCE SCHEDULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
9-3 SPARK ARRESTER (OPTIONAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
9-4 ENGINE STORAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .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.)
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.
•
Maximum Torque N
(ft•lb. / r.p.m.)
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
Capacity of Lubricant L (U.S. gal.) 1.55 (0.41)
Throttle body Electronic Fuel injection
m / r.p.m.
(kgf•m / r.p.m.)
Automobile engine oil SAE #20, #30 or 10W-30;
2 - 84 × 65 (3.31 × 2.56)
Net : 17.9 (24.0) / 3600
Gross : 19.4 (26.1) / 3600
20.9 (28.0) / 4000
52.2 / 2800
(5.32 / 2800)
(38.5 / 2800)
Class SE or higher
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.)
Dimensions
(L×W×H) mm (in.)
Specifications are subject to change without notice.
*
with out muffler and control box 46 (101.3)
with STD muffler and control box 51.5 (113.4)
with out muffler and control box
with STD muffler and control box
317×477×480 (12.5×18.8×18.9)
464×499×480 (18.3×19.6×18.9)
- 1 -
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 lowtemperature.
- 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.
- 2 -
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.
PULSATION DAMPER
FUEL PRESSURE
REGULATOR
ECU
ECU (Engine Control Unit)
THROTTLE
BODY AY
THROTTLE
BODY AY
INJECTOR
CLEANER
ADAPTER
ELECTRIC
FUEL PUMP
OIL / FAIL
WARNING
LAMP
(OPTION)
INTAKE
MANIFOLD
TEMPERATURE
SENSOR
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”.)
- 3 -
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
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4-3 DISASSEMBLY PROCEDURES (DIFFERENCE)
Step Parts to remove Remarks and procedures Parts Fasteners
8 Choke lever Choke lever not applicable.
Governor rod (1) Remove the governor rod spring from rod holder.
9
STEP 9
GOVERNOR SHAFT
GOVERNOR LEVER
(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.
L
R
M6 bolt and washer : 1pc.
THROTTLE BODY
ROD HOLDER
ROD SPRING
- 5 -
A
GOVERNOR ROD
GOVERNOR
ROD
ROD HOLDER
Fig. 4-1
Turn the rod holder
clockwise to loosen.
VIEW A
Step Parts to remove Remarks and procedures Parts Fasteners
Throttle body (1) Disconnect the two connectors from ECU under the
throttle body.
10
STEP 10
(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.
CLEANER
CONNECTER
(INJECTOR)
CONNECTER
(ECU)
ADAPTER
M6 Flange nut : 4pcs.
CONNECTER
(INJECTOR)
GOVERNOR LEVER
- 6 -
M6 FLANGE NUT
Step Parts to remove Remarks and procedures Parts Fasteners
Fuel pump (1) Disconnect the connecter places from fuel pump wiring harness 2.
13
(2) Remove fuel pump ASSY and detach bracket.
M6 x 12 Flange bolt : 1 pc.
PLUG
TERMINAL
SPARK
PLUG CAP
#1 CYLINDER SIDE
TO THROTTLE BODY
(ECU)
#2 CYLINDER SIDE
#1
IGNITION
COIL
STEP 14
M6 BOLT AND
WASHER ASSY
GROMMT
(PLUG CAP)
#2 CYLINDER
SIDE ONLY
CONNECTER
(FUEL PUMP)
M6 BOLT AND
WASHER ASSY
#2
IGNITION
COIL
PLUG TERMINAL
SPARK PLUG CAP
TO THROTTLE BODY
(ECU) and KEY SWITCH
HOSE
CLAMP
FUEL
PIPE
HOSE
CLAMP
HOSE CLAMP
- 7 -
HOSE CLAMP
M6 FLANGE BOLT
FUEL PUMP
STEP 13
FUEL FILTER
Step Parts to remove Remarks and procedures Parts Fasteners
Regulator and Wire CP (1) Disconnect wire connector from regulator, and then
M6 x 12 Flange bolt : 2 pcs.
remove regulator from #1 cylinder baffle.
Tapping screw : 1pc.
16
(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)
21 Spark plug Take care the spark plug is hot just after stopping engine. NGK : BPR5ES or BPR4EY
STEP 16
WIRING HARNESS
TO KEY
SWITCH
WHITE
#1 CYLINDER SIDE
M8 FLANGE NUT
STEP 15
GASKET
INTAKE MANIFOLD
M6 FLANGE
BOLT
STEP 16
CONNECTER
(GRAY)
Gry(Grn/R)
REGULATOR
TO THROTTLE BODY
TAPPING
SCREW
TEMPERATURE SENSOR
WIRING HARNESS 1
INJECTOR #1
Blk(Grn/R)
Blk(Blk/Blk)
Blk(Blk)
Gry(Blk)
CYLINDER
BAFFLE #1
(ECU)
INJECTOR #2
TEMPERATURE
SENSOR
TO IGNITION COIL #2
TO IGNITION COIL #1
#2 CYLINDER SIDE
CONNECTER
(BLACK)
Blk(R)
WIRING HARNESS 2
FUEL PUMP
Blk(Blk)
Blk
(Blk)
(Blk)
Blk(R)
Blk
Blk(W)
Blk(Blk)
M8 FLANGE
NUT
GASKET
POWER
GROUND
WARNING
LAMP
IG COIL
GROUND
BATTERY
R
TO THROTTLE
BODY "L"SIDE
WIRING COLOR CODE
Blk : Black Gry : Gray R : Red Grn : Green W : Wite
TO THROTTLE
BODY "R"SIDE
( ) is inside wiring color code.
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