TROUBLESHOOTING
9-1
EAM20148
TROUBLESHOOTING
EAM30309
GENERAL INFORMATION
TIP
The following guide for troubleshooting does not
cover all the possible causes of trouble. It should
be helpful, however, as a guide to basic trouble-
shooting. Refer to the relative procedure in this
manual for checks, adjustments, and replace-
ment of parts.
EAM30310
STARTING FAILURES
Engine
1. Cylinder and cylinder head
•
Loose spark plug
•
Loose cylinder head or cylinder
•
Damaged cylinder head gasket
•
Damaged cylinder gasket
•
Worn or damaged cylinder
•
Incorrect valve clearance
•
Improperly sealed valve
•
Incorrect valve-to-valve-seat contact
•
Incorrect valve timing
•
Faulty valve spring
•
Seized valve
2. Piston and piston ring(s)
•
Improperly installed piston ring
•
Damaged, worn or fatigued piston ring
•
Seized piston ring
•
Seized or damaged piston
3. Air filter
•
Improperly installed air filter
•
Clogged air filter element
4. Crankcase and crankshaft
•
Improperly assembled crankcase
•
Seized crankshaft
Fuel system
1. Fuel tank
•
Empty fuel tank
•
Clogged fuel tank breather hose
•
Deteriorated or contaminated fuel
•
Clogged or damaged fuel hose
2. Fuel pump
•
Faulty fuel pump
3. Throttle body
•
Deteriorated or contaminated fuel
•
Sucked-in air
Electrical system
1. Battery
•
Discharged battery
•
Faulty battery
2. Fuse
•
Blown, damaged or incorrect fuse
•
Improperly installed fuse
3. Spark plug
•
Incorrect spark plug gap
•
Incorrect spark plug heat range
•
Fouled spark plug
•
Worn or damaged electrode
•
Worn or damaged insulator
4. Ignition coil
•
Cracked or broken ignition coil body
•
Broken or shorted primary or secondary coils
5. Ignition system
•
Faulty ECU
•
Faulty crankshaft position sensor
•
Broken generator rotor woodruff key
6. Switches and wiring
•
Faulty ECU
•
Faulty engine stop switch
•
Broken or shorted wiring
•
Faulty neutral switch
•
Improperly grounded circuit
•
Loose connections
7. Starting system
•
Faulty starter motor
•
Faulty starter relay
•
Faulty starting circuit cut-off relay
•
Faulty starter clutch
EAM30311
INCORRECT ENGINE IDLING SPEED
Engine
1. Cylinder and cylinder head
•
Incorrect valve clearance
•
Damaged valve train components
2. Air filter
•
Clogged air filter element
Fuel system
1. Throttle body
•
Damaged or loose throttle body joint
•
Improperly synchronized throttle bodies
•
Improper throttle cable free play
•
Flooded throttle body
Electrical system
1. Battery
•
Discharged battery
•
Faulty battery
2. Spark plug
•
Incorrect spark plug gap
•
Incorrect spark plug heat range
•
Fouled spark plug
•
Worn or damaged electrode
•
Worn or damaged insulator
•
Faulty spark plug cap
Summary of Contents for YZ 2019 Series
Page 6: ...EAM20162 YAMAHA MOTOR CORPORATION U S A YZ MOTORCYCLE LIMITED WARRANTY...
Page 10: ......
Page 40: ...MOTORCYCLE CARE AND STORAGE 1 28...
Page 63: ...LUBRICATION POINTS AND LUBRICANT TYPES 2 22...
Page 66: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 25...
Page 68: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 27...
Page 70: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 29...
Page 72: ...CABLE ROUTING DIAGRAM 2 31 EAM20152 CABLE ROUTING DIAGRAM...
Page 74: ...CABLE ROUTING DIAGRAM 2 33...
Page 76: ...CABLE ROUTING DIAGRAM 2 35...
Page 78: ...CABLE ROUTING DIAGRAM 2 37...
Page 80: ...CABLE ROUTING DIAGRAM 2 39...
Page 82: ...CABLE ROUTING DIAGRAM 2 41...
Page 84: ...CABLE ROUTING DIAGRAM 2 43...
Page 86: ...CABLE ROUTING DIAGRAM 2 45...
Page 126: ...ELECTRICAL SYSTEM 3 38...
Page 177: ...FRONT FORK 4 49 1...
Page 196: ...CHAIN DRIVE 4 68...
Page 217: ...CAMSHAFT 5 18 Spark plug Spark plug 13 N m 1 3 kgf m 9 6 lb ft T R...
Page 237: ...ELECTRIC STARTER 5 38...
Page 256: ...OIL PUMP AND BALANCER GEAR 5 57 a 2 10 b 2 9 1 b 5 3 a 4 10 5 9 3 E c d 6 7 8 8 b 6...
Page 262: ...GENERATOR AND STARTER CLUTCH 5 63 1 a 3 3 2 4...
Page 276: ...TRANSMISSION 5 77...
Page 284: ...WATER PUMP 6 7...
Page 290: ...FUEL TANK 7 5 A Left B Right 1 1 A 0 mm 0 in B 1 1 15 mm 0 59 in...
Page 296: ...THROTTLE BODY 7 11...
Page 299: ......
Page 313: ...CHARGING SYSTEM 8 14...
Page 343: ...FUEL INJECTION SYSTEM 8 44...
Page 347: ...FUEL PUMP SYSTEM 8 48...
Page 348: ...ELECTRICAL COMPONENTS 8 49 EAM20147 ELECTRICAL COMPONENTS 9 10 1 3 2 4 5 6 7 8...
Page 350: ...ELECTRICAL COMPONENTS 8 51 11 10 9 2 3 1 6 7 8 4 5...
Page 352: ...ELECTRICAL COMPONENTS 8 53 EAM30289 CHECKING THE SWITCHES 4 1 3 2 B B Sb B B B B B B B B...
Page 368: ...ELECTRICAL COMPONENTS 8 69...
Page 376: ...LIST OF SELF DIAGNOSTIC AND FAIL SAFE ACTIONS 9 7...