engine YAMAHA YZ250F 2016 Owners Manual

WATER PUMP
6-6
EAS1SM9298REMOVING THE OIL SEAL
TIP
• Remove the oil seal when the coolant level
changes frequently more than usual, coolant
has discolored, or engine oil has become
milky.
• Do not use the removed oil seal.
1. Remove:
• Oil seals “1”
EAS1SM9299CHECKING THE WATER PUMP
1. Check:
• Water pump housing cover
• Impeller shaft
Cracks/damage/wear  Replace.
EAS1SM9300CHECKING THE BEARING
1. Check:
• Bearing
Rotate the inner race with your finger.
Rough spot/seizure  Replace.
EAS1SM9301INSTALLING THE OIL SEAL
1. Install:
• Oil seals “1”
TIP
• Apply the lithium-soap-based grease on the
oil seal lip.
• Install the oil seal with its manufacture’s
marks or numbers facing the right crankcase
cover “2”.2. Install:
• Bearing “1”
TIP
Install the bearing by pressing its outer race
parallel.
EAS1SM9302ASSEMBLING THE WATER PUMP
1. Install:
• Impeller shaft assembly “1”
• Washer “2”
•Pin “3”
• Gear “4”
• Collar “5”
• Circlip “6”
TIP
• Take care so that the oil seal lip is not dam-
aged or the spring does not slip off its posi-
tion.
• When installing the impeller shaft, apply the
engine oil to the oil seal lip, the bearing, and
the impeller shaft.
1 1
New
1 1New
New
LS
LS2
New
1
2
52346
New
E

FUEL TANK
7-1
EAS1SM9303
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.
EAS1SM9304
FUEL TANK
Removing the fuel tank
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right)
Air scoop (left/right)
1 Fuel pump coupler 1 Disconnect.
2 Fuel hose 1 Disconnect.
3Fuel tank 1
4 Fuel pump bracket 1
5 Fuel pump 1
6 Fuel pump gasket 1
For installation, reverse the removal proce-
dure.
4(6) (2)
(2) (2)(2)2
5
6
3
1
New
4.0 Nm (0.40 m kgf, 2.9 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
7 Nm (0.7 m kgf, 5.1 ft Ibf)T.R.
9 Nm (0.9 m kgf, 6.5 ft Ibf)T.R.
4.0 Nm (0.40 m kgf, 2.9 ft Ibf)T.R.
4.0 Nm (0.40 m kgf, 2.9 ft Ibf)T.R.
7

FUEL TANK
7-4
e. Start the engine.
f. Measure the fuel pressure.
Out of specification  Replace the fuel
pump.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲EAS1SM9311CHECKING THE DAMPER
1. Check:
• Damper 1 “1”
• Damper 2 “2”
• Damper 3 “3”
Wear/damage  Replace.
TIP
• Affix dampers 1 and 3 with the arrow on each
damper pointing outward.
• Affix the damper 2 with its projection “a” facing
the rear of the vehicle.
EAS1SM9312CHECKING AND REPLACING THE PRO-
TECTOR
1. Check:
• Protector “1”
Wear/damage  Replace.
TIP
Affix the protector as shown.
Fuel line pressure at idling
324.0 kPa (3.24 kgf/cm
2, 47.0
psi)
1
2
(3.31 in) (4.53 in)
84 mm 115 mm3 1
13a
2
(3.31 in) (4.53 in)84 mm 115 mm
A. Left
B. Right
1
1
A
0 mm
(0 in)
B
1
1
15 mm
(0.59 in)

THROTTLE BODY
7-5
EAS1SM9313
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
7-8
EAS1SM9314CHECKING THE INJECTOR
1. Check:
• Injectors
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.
EAS1SM9315CHECKING THE THROTTLE BODY
1. Check:
• Throttle body
Cracks/damage  Replace.
2. Check:
• Fuel passages
Obstructions  Clean.
ECA
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.
EAS1SM9316CHECKING THE THROTTLE BODY JOINT
1. Check:
• Throttle body joint “1”
Crack/damage  Replace.
1 2
3
ba
c
1

8-1
EAS1SM9318
TIP
This section is intended for those who have basic knowledge and skill concerning the servicing of
Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl-
edge and skill concerning servicing are requested not to undertake inspection, adjustment, disas-
sembly, or reassembly only by reference to this manual. It may lead to servicing trouble and
mechanical damage.

IGNITION SYSTEM
8-3
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
18.Ignition coil sub-lead

IGNITION SYSTEM
8-4
EAS1SM9321TROUBLESHOOTING
The ignition system fails to operate (no spark or intermittent spark).
TIP
Before troubleshooting, remove the following part(s):
1. Side cover (left/right)
2. Seat
3. Fuel tank
4. Air scoop (left/right)
5. Air filter case cover
1. Check the ignition system wire har-
ness connections.NG 
Reconnect.
OK 
2. Check the spark plug.
Refer to “CHECKING THE SPARK
PLUG” on page 3-36.NG 
Correct or replace the spark plug.
OK 
3. Check the ignition spark gap.
Refer to “CHECKING THE IGNI-
TION SPARK GAP” on page 8-41.OK 
The ignition system circuit is OK.
NG 
4. Check the ignition coil.
Refer to “CHECKING THE IGNI-
TION COIL” on page 8-41.NG 
Replace the ignition coil.
OK 
5. Check the engine stop switch.
Refer to “CHECKING THE
SWITCHES” on page 8-38.NG 
Replace the engine stop switch.
OK 
6. Check the crankshaft position sen-
sor.
Refer to “CHECKING THE CRANK-
SHAFT POSITION SENSOR” on
page 8-42.NG 
Replace the crankshaft position sensor.
OK 
7. Check the stator coil.
Refer to “CHECKING THE STA-
TOR COIL” on page 8-43.NG 
Replace the stator coil.
OK 

FUEL INJECTION SYSTEM
8-11
1. Crankshaft position sensor
2. AC magneto
3. Rectifier/regulator
4. Joint connector
5. Condenser
7. Engine stop switch
8. Neutral switch
9. ECU (electronic control unit)
12.Fuel injector
13.Fuel pump
14.Intake air temperature sensor
15.Coolant temperature sensor
16.Throttle position sensor
17.Intake air temperature sensor

FUEL INJECTION SYSTEM
8-13
2. Connect the FI diagnostic tool sub-lead.
3. Connect the FI diagnostic tool sub-lead to the battery.
TIP
• Prepare the fully charged 12 V battery for yourself.
• For information on how to connect and use the Yamaha diagnostic tool, refer to “YAMAHA DIGNO-
STIC TOOL OPERATION MANUAL”.
EAS1SM9327TROUBLESHOOTING DETAILS
This section describes the measures per fault code No. displayed on the Yamaha diagnostic tool.
Check and service the items or components that are the probable cause of the malfunction following
the order given in the troubleshooting chart.
After the check and service of the malfunctioning part have been completed, reset the Yamaha diag-
nostic tool display according to the “Reinstatement method”.
Fault code No.: To be displayed on the Yamaha diagnostic tool when the engine fails to work nor-
mally
Diagnostic code No.: To be used when the diagnostic mode is active FI diagnostic tool sub-lead
90890-03212
YU-03212
1. Vehicle
2. Coupler for connecting optional part
3. FI diagnostic tool sub-lead
4. Sub-harness (included with the Yamaha di-
agnostic tool)
5. Vehicle communication cable (included with
the Yamaha diagnostic tool)
6. Yamaha diagnostic tool
7. Battery (12 V)
1
3 2
2456
7