2012 YAMAHA YZ450F Valve

6-6
THROTTLE BODY
CHECKING THE INJECTOR
Replace the fuel injector with a
new one if you have dropped or im-
pacted it.
1. Check:
• Injectors
Damage → Replace.
CHECKING THE THROTTLE BODY
•Before removing the throttle
body, clean the area around the
throttle body to prevent dirt and
other foreign material from fall-
ing into the engine.
•If the throttle body is subject to
strong shocks or dropped during
cleaning, replace it.
•Do not use any caustic carbure-
tor cleaning solution.
•Do not directly push the throttle
valves to open them.
•Do not loosen the throttle valve
stopper screw "1", throttle valve
pulley nut "2", or throttle valve
screw "3". Otherwise, a loss of
performance may occur.
•Do not use compressed air to
clean the throttle body. Other-
wise, foreign material may ad-
here to the intake air pressure
sensor passage "a" and fuel in-
jector "b" in the throttle body.
1. Check:
• Throttle body
Cracks/damage → Replace the
throttle body as a set.
2. Check:
• Starter knob/ idle screw delivery
passages "a"
Obstructions →Blow out with
compressed air.
ASSEMBLING THE THROTTLE
BODY
1. Install:
• O-ring "1"
• Injector "2"
•Bolt "3"
Always use a new O-ring.
INSTALLING THE THROTTLE
BODY
1. Install:
• Throttle body joint "1"
• Throttle body "2"
• Face the slot "a" in the throttle body
joint toward the bottom of the vehi-
cle.
•Align the slot "a" on the throttle body
joint with the projection "b" on the
throttle body.
2. Install the water-resistant cover
"1" onto the throttle body.
CHECKING AND REPLACING THE
PROTECTOR
1. Check:
• Protector "1"
Wear/damage → Replace.
Affix the protector as shown.Bolt (injector)
3 Nm (0.3 kg•m, 2.2
ft•lb)
Throttle body joint clamp
screw
3 Nm (0.3 m•kg, 2.2
ft•lb)

7-12
FUEL INJECTION SYSTEM
D36 Injectors ActuationCheck that power is supplied to
the fuel injector.
• Check the fuel injector operation
by listening for the operating
sound or by confirming the oper-
ation visually.Actuates the injector for five times
every second.
The "WARNING" LED on the FI di-
agnostic tool comes on each time
the fuel injector is actuated.
D60EEPROM fault code
display.DisplayDisplays the abnormal portion of
the data in the EEPROM that has
been detected as a fault code No.
44.
If code numbers more than one
are detected, the display alter-
nates every two seconds to show
all the detected code numbers.
When all code numbers are
shown, the display repeats the
same process.00: No fault
01: CO adjustment valve
07: Power Tuner adjustment val-
ues 0–8 for fuel injection amount or
ignition timing
D61Malfunction history
code display.DisplayDisplays the fault code numbers
that are stored in the malfunction
history.
If code numbers more than one
are detected, the display alter-
nates every two seconds to show
all the detected code numbers.
When all code numbers are
shown, the display repeats the
same process.00: No history
12–50: History exists
• Refer to the fault code number.
D62Malfunction history
code erasureActuation
and displayDisplays the total number of mal-
functions, including the current
malfunction, that have occurred
since the history was last erased.
In addition, deletes the fault code
numbers from the history if the cor-
responding items are currently op-
erating normally.00: No history
1–15: History exists
When this diagnostic code number
is selected, fault code numbers for
previously detected malfunctions
are deleted from the history if the
corresponding items are currently
operating normally.
D64 Setting history display DisplayDisplays whether or not history ex-
ists for settings that were made us-
ing the Power Tuner.00: There is no setting history.
01: There is setting history.
02: Whether or not setting history
data exists cannot be determined
(damage to history data).
D65 Setting map erasure DisplayErases the settings that were
made using the Power Tuner.00: There are no settings that were
made using the Power Tuner.
01: There are settings that were
made using the Power Tuner.
D70Program version
numberDisplayCheck the version number of the
program.0–254 Diagnos-
tic code
No.ItemActuation or
displayChecking methodActuation or LCD standard display
values

7-17
FUEL INJECTION SYSTEM
Fault code No. 15
Symptom Throttle position sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D01
FI diagnostic tool display • 15–19° (Fully closed position)
• 95–101° (Fully opened position)
Checking method• Check with throttle valves fully closed.
• Check with throttle valves fully open.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the throttle position sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between throttle position sensor
coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Yellow–Yellow)
(Blue–Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor.
• Make sure that the installation position is cor-
rect.
• Make sure that there are no problems with the
installation.Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.
Incorrect installation position →
Properly install.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.

7-18
FUEL INJECTION SYSTEM
5 Applied voltage of throttle position sensor lead Measure the output voltage.
Refer to "CHECKING THE
THROTTLE POSITION SEN-
SOR".Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 6. Open circuit
itemApplied voltage
Ground wire
open circuit5 V
Output wire
open circuit0 V
Power supply
wire open circuit0 V
6 Defective throttle position sensor. Execute the diagnostic mode (di-
agnostic code No. D01).
When throttle is fully closed: A
value of 15–19 is indicated.
When throttle is fully opened: A
value of 95–101 is indicated.
Displayed value is out of specifica-
tion → Replace. Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 7.
7 Malfunction in ECU. Replace the ECU. Fault code No. 15
Symptom Throttle position sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D01
FI diagnostic tool display • 15–19° (Fully closed position)
• 95–101° (Fully opened position)
Checking method• Check with throttle valves fully closed.
• Check with throttle valves fully open.
Item Item/components and probable cause Check or maintenance job Checking method

7-19
FUEL INJECTION SYSTEM
Fault code No. 16
Symptom Signal from throttle position sensor does not change.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D01
FI diagnostic tool display • 15–19° (Fully closed position)
• 95–101° (Fully opened position)
Checking method• Check with throttle valves fully closed.
• Check with throttle valves fully open.
Item Item/components and probable cause Check or maintenance job Checking method
1 Installed condition of sensor.
• Make sure that the installation position is cor-
rect.
• Make sure that there are no problems with the
installation.Check that the sensor is installed
securely and that there are no
pinched leads. Check that the
ECU is installed securely and that
there are no pinched leads.
Incorrect installation → Reinstall
or repair.
Incorrect installation position →
Properly install.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
operate the throttle.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Defective throttle position sensor. Execute the diagnostic mode (di-
agnostic code No. D01).
When throttle is fully closed: A
value of 15–19 is indicated.
When throttle is fully opened: A
value of 95–101 is indicated.
Displayed value is out of specifica-
tion → Replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
operate the throttle.
After completing the above
operation, check whether a
fault code number is dis-
played.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Malfunction in ECU. Replace the ECU.

7-30
FUEL INJECTION SYSTEM
Fault code No. 44
Symptom Error is detected while reading or writing on EEPROM.
Fail-safe system Able to start engine (depending on circumstances)
Able to drive vehicle (depending on circumstances)
Diagnostic code No. D60
FI diagnostic tool display 00: No fault
01: CO adjustment valve
07: Power Tuner adjustment values 0–8 for fuel injection amount or ignition timing
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Determine the area of the problem Execute the diagnostic mode (di-
agnostic code No. D60).
00 is displayed: Refer to item 4.
01 is displayed: Refer to item 2.
07 is displayed: Refer to item 3.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Repeat item 1.
If the fault code number
is still displayed, refer to
item 3.
2 EEPROM data error (CO adjustment value) Change the CO density and write
the changed setting on EEPROM.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Repeat item 1.
If the fault code number
is still displayed, refer to
item 4.
3 EEPROM data error (Power Tuner adjustment
values for fuel injection amount or ignition tim-
ing)Erase the setting map in the diag-
nostic mode (diagnostic code No.
D65).Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 1.
4 Malfunction in ECU. Replace the ECU.