2013 YAMAHA YZ450F fuel pressure

7-23
FUEL INJECTION SYSTEM
Fault code No. 23
Symptom Atmospheric pressure sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D02
FI diagnostic tool display Atmosphere
Checking method Measure the atmospheric pressure.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the atmospheric pressure 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 atmospheric pressure
sensor coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Pink–Pink)
(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. 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.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.

7-24
FUEL INJECTION SYSTEM
5 Defective atmospheric pressure sensor. Execute the diagnostic mode (di-
agnostic code No. D02).
When the engine is stopped,
displays the atmospheric pres-
sure according to the elevation
and weather.
0 m above sea level: Approx.
101 kPa
1000 m above sea level: Ap-
prox. 90 kPa
2000 m above sea level: Ap-
prox. 80 kPa
3000 m above sea level: Ap-
prox. 70 kPa
Displayed value is incorrect → Re-
place.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.
6 Malfunction in ECU. Replace the ECU. Fault code No. 23
Symptom Atmospheric pressure sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D02
FI diagnostic tool display Atmosphere
Checking method Measure the atmospheric pressure.
Item Item/components and probable cause Check or maintenance job Checking method

7-35
FUEL PUMP SYSTEM
FUEL PUMP SYSTEM
INSPECTION STEPS
If the fuel pump is not operating normally, perform the following procedures in the order given.
• Remove the following parts before inspection.
1. Seat
2. Side cover (right/left)
3. Fuel tank
• Use the following special tools in this inspection.
Check engine stop switch. No good→Replace.
OK ↓
Checking the couplers and leads connections No good→Repair or replace.
OK ↓
Check the fuel pump.(Checking the fuel pump
body)No good→
Replace the fuel pump assembly.
OK ↓
Replace the ECU.
Pocket tester:
YU-03112-C/90890-03112
Test harness S-pressure sensor (3P):
YU-03207/90890-03207

7-37
ELECTRICAL COMPONENTS
3. Connect the FI diagnostic tool
sub-wire harness to a battery, and
then set the switch on the harness
to "ON".
When checking the atmospheric
pressure sensor, do not start the
engine.
4. Measure the atmospheric pres-
sure sensor output voltage.
Out of specification→Replace.
CHECKING THE RECTIFIER/
REGULATOR
1. Connect:
• Connect the tester to the coupler
for connecting optional part
Tester (+) lead→ Red lead "1"
Tester (-) lead→ Black/White lead
"2"
2. Start the engine.
3. Check:
• Rectifier/regulato output voltage
Out of specification → Replace.
4. Stop the engine.CHECKING THE FUEL INJECTORS
1. Remove:
•Seat
•Fuel tank
• Air filter case
2. Check:
•Injector resistance
3. Connect:
•Tester
Tester (+) lead → Injector termi-
nal "1"
Tester (-) lead → Injector termi-
nal "2"
Out of specification→Replace. Test harness S–pressure
sensor (3P):
YU-03207/90890-03207
Output volt-
ageTester se-
lector posi-
tion
3.4–3.8 V DCV
Output volt-
ageTester se-
lector posi-
tion
14.1–14.9 V DCV
Lg
R
B/W
Injector re-
sistanceTester se-
lector posi-
tion
12.0 Ω
(20°C, 68°F) Ω×10