sensor YAMAHA YZ250F 2014 User Guide

AC MAGNETO
5-58
EAS1SM1272
AC MAGNETO
Removing the AC magneto
Order Part name Q’ty Remarks
Engine oilDrain.
Refer to “CHANGING THE ENGINE OIL” on
page 3-15.
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left) Refer to “GENERAL CHASSIS” on page 4-1.
1 AC magneto lead Disconnect.
2 Crankshaft position sensor lead 1 Disconnect.
3 Shift pedal 1
4 Left crankcase cover 1
5 Gaskets 1
6 Dowel pin 2
7Holder 1
8 Stator assembly 1
9 Rotor 1
10 Woodruff key 1
For installation, reverse the removal proce-
dure.
110
2
4 7 5 8 3
96
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
65 Nm (6.5 mkgf, 47 ftIbf)T.R.
New
LT
6
LT
LT
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.

AC MAGNETO
5-59
EAS1SM1273REMOVING THE AC MAGNETO
1. Remove:
• Nut (rotor) “1”
• Washers
2. Remove:
• Rotor “1”
Use the rotor puller “2” to remove the rotor.
• Woodruff key
EAS1SM1274CHECKING THE AC MAGNETO
1. Check:
• Rotor inner surface “a”
• Stator outer surface “b”
Damage  Inspect the crankshaft runout
and crankshaft bearing.
EAS1SM1275
CHECKING THE WOODRUFF KEY
1. Check:
• Woodruff key “1”
Damage  Replace.
EAS1SM1276INSTALLING THE AC MAGNETO
1. Install:
• Stator “1”
• Screw (stator) “2”
• Crankshaft position sensor “3”
• Bolt (crankshaft position sensor) “4”
• Holder “5”
• Bolt (holder) “6”
TIP
• Apply the sealant to the grommet of the AC
magneto lead.
• Tighten the stator screws using the T25 bit.
• Pass the AC magneto lead “a” through the
crankcase cover side. Rotor puller
90890-04151
YM-04151
1
ab
Screw (stator)
8 Nm (0.8 m·kgf, 5.8ft·lbf)
LOCTITE®
Bolt (crankshaft position sensor)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
Holder
8 Nm (0.8 m·kgf, 5.8 ft·lbf)
LOCTITE®
Three Bond No.1215®
90890-85505
T R..
T R..
26
5
4
3
4a
1
LT
LT

RADIATOR
6-2
3 Right radiator 1
4 Radiator hose 2 1
5 Radiator hose 3 1
6 Radiator hose 4 1
7 Radiator pipe 2 1
8 Radiator breather hose 1
9 Left radiator 1
10 Radiator hose 1 1
11 Radiator pipe 1 1
12 Coolant temperature sensor 1
For installation, reverse the removal proce-
dure.
Removing the radiator
Order Part name Q’ty Remarks
11
12
New
New
New
LS
LS

7
FUEL SYSTEM
FUEL TANK...................................................................................................... 7-1
REMOVING THE FUEL TANK ................................................................... 7-2
REMOVING THE FUEL PUMP .................................................................. 7-2
CHECKING THE FUEL PUMP BODY........................................................ 7-2
INSTALLING THE FUEL PUMP ................................................................. 7-2
INSTALLING THE FUEL TANK.................................................................. 7-3
CHECKING THE FUEL PRESSURE ......................................................... 7-3
CHECKING THE DAMPER ........................................................................ 7-4
CHECKING AND REPLACING THE PROTECTOR .................................. 7-4
THROTTLE BODY............................................................................................ 7-5
CHECKING THE INJECTOR ..................................................................... 7-8
CHECKING THE THROTTLE BODY ......................................................... 7-8
CHECKING THE THROTTLE BODY JOINT .............................................. 7-8
ADJUSTING THE THROTTLE POSITION SENSOR................................. 7-9

THROTTLE BODY
7-5
EAS1SM1315
THROTTLE BODY
Removing the throttle body
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
ECU Refer to “ENGINE REMOVAL” on page 5-1.
Ignition coil Refer to “ENGINE REMOVAL” on page 5-1.
1 Intake air temperature sensor coupler 1 Disconnect.
2 Air filter case 1
3 Fuel injector coupler 1 Disconnect.
4 Intake air pressure sensor coupler 1 Disconnect.
5 Throttle position sensor coupler 1 Disconnect.
6 Throttle cable cover 1
7 Throttle cable 2
8 Fuel hose 1
9 Exhaust pipe bracket 1
2
1
6
10
11
9
8
3
7
5
4
3.5 Nm (0.35 mkgf, 2.5 ftIbf)T.R
.
3.5 Nm (0.35 mkgf, 2.5 ftIbf)T.R
.
7 Nm (0.7 mkgf, 5.1 ftIbf)T.R.
3.0 Nm (0.30 mkgf, 2.2 ftIbf)T.R
.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.

THROTTLE BODY
7-7
Removing the injector
Order Part name Q’ty Remarks
1 Fuel inlet pipe 1
2Injector 1
3 Gaskets 1
4 Throttle position sensor 1
5 Intake air pressure sensor 1
For installation, reverse the removal proce-
dure.
1
2 (2)
(2)5
43
T.R.3.4 Nm (0.34 mlbf) kgf, 2.5 ft
T.R.5 Nm (0.5 mlbf) kgf, 3.6 ft
T.R.3.4 Nm (0.34 mlbf) kgf, 2.5 ft

THROTTLE BODY
7-8
EAS1SM1316CHECKING THE INJECTOR
1. Check:
• Injector
Obstruction  Replace, and check the fuel
pump and the fuel injection system.
Refer to “FUEL INJECTION SYSTEM” on
page 8-10.
Deposits  Replace.
Damage  Replace.
2. Check:
• Injector resistance
Refer to “CHECKING THE FUEL INJEC-
TOR” on page 8-47.
EAS1SM1317CHECKING THE THROTTLE BODY
1. Check:
• Throttle body
Cracks/damage  Replace.
2. Check:
• Fuel passages
Obstructions  Clean.
ECA1DX1027
NOTICE
• Before removing the throttle body, clean
the area around the throttle body to pre-
vent dirt and other foreign material from
falling into the engine.
• If the throttle body is subject to strong
shocks or dropped during cleaning, re-
place it.
• Do not use any caustic carburetor clean-
ing 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”. A loss of perfor-
mance may occur.
• Do not use compressed air to clean the
throttle body. Foreign materials may ad-
here to the intake air pressure sensor pas-
sage “a” and fuel injector “b” in the
throttle body.3. Check:
• Starter knob/idle screw passage “c”
Obstruction  Blow out with compressed
air.
EAS1SM1318CHECKING THE THROTTLE BODY JOINT
1. Check:
• Throttle body joint “1”
Crack/damage  Replace.
EAS1SM1319
1 2
3
ba
c
1

THROTTLE BODY
7-9
ADJUSTING THE THROTTLE POSITION
SENSOR
EWA32D1011
WARNING
• Handle the throttle position sensor with
special care.
• Never subject the throttle position sensor
to strong shocks. If the throttle position
sensor is dropped, replace it.
1. Check:
• Throttle position sensor
Refer to “CHECKING THE THROTTLE PO-
SITION SENSOR” on page 8-44.
2. Adjust:
• Throttle position sensor angle
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the Yamaha diagnostic tool.
Refer to “YAMAHA DIAGNOSTIC TOOL” on
page 8-12.
b. Temporary tighten the throttle position sen-
sor.
c. Check that the throttle grip is fully closed.
d. Connect the throttle position sensor to the
wire harness.
e. Set the Yamaha diagnostic tool to “diagnos-
tic mode”.
f. Choose the diagnostic code No. “01”.
g. Adjust the throttle position sensor mounted
angle until “11–14” appears on the Yamaha
diagnostic tool.
h. After adjusting the throttle position sensor
mounted angle, tighten the throttle position
sensor screws “1”.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Yamaha diagnostic tool
90890-03215
Throttle position sensor screw
3.4 Nm (0.34 m·kgf, 2.5 ft·lbf)
T R..
1

8
ELECTRICAL SYSTEM
IGNITION SYSTEM.......................................................................................... 8-2
CIRCUIT DIAGRAM ................................................................................... 8-2
TROUBLESHOOTING ............................................................................... 8-4
CHARGING SYSTEM....................................................................................... 8-6
CIRCUIT DIAGRAM ................................................................................... 8-6
TROUBLE SHOOTING .............................................................................. 8-8
FUEL INJECTION SYSTEM........................................................................... 8-10
CIRCUIT DIAGRAM ................................................................................. 8-10
YAMAHA DIAGNOSTIC TOOL ................................................................ 8-12
TROUBLESHOOTING DETAILS ............................................................. 8-13
FUEL PUMP SYSTEM.................................................................................... 8-32
CIRCUIT DIAGRAM ................................................................................. 8-32
TROUBLESHOOTING ............................................................................. 8-34
ELECTRICAL COMPONENTS....................................................................... 8-36
.................................................................................................................. 8-36
CHECKING THE SWITCHES .................................................................. 8-38
CHECKING THE IGNITION SPARK GAP................................................ 8-41
CHECKING THE SPARK PLUG CAP ...................................................... 8-41
CHECKING THE IGNITION COIL ............................................................ 8-41
CHECKING THE CRANKSHAFT POSITION SENSOR........................... 8-42
CHECKING THE ECU .............................................................................. 8-43
CHECKING THE STATOR COIL ............................................................. 8-43
CHECKING THE RECTIFIER/REGULATOR ........................................... 8-43
CHECKING THE COOLANT TEMPERATURE SENSOR........................ 8-44
CHECKING THE THROTTLE POSITION SENSOR ................................ 8-44
CHECKING THE THROTTLE POSITION SENSOR
INPUT VOLTAGE .................................................................................... 8-45
CHECKING THE INTAKE AIR PRESSURE SENSOR ............................ 8-46
CHECKING THE INTAKE AIR TEMPERATURE SENSOR ..................... 8-46
CHECKING THE NEUTRAL SWITCH ..................................................... 8-46
CHECKING THE FUEL INJECTOR ......................................................... 8-47

IGNITION SYSTEM
8-3
EAS1SM1323
1. Crankshaft position sensor
2. AC magneto
3. Rectifier/regulator
4. Joint connector
5. Condenser
7. Engine stop switch
9. ECU
10.Ignition coil
11.Spark plug