Yamaha YFM25RY Automobile User Manual


 
TROUBLESHOOTING
8-1
EAS28451
TROUBLESHOOTING
EAS28460
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
troubleshooting. Refer to the relative proce-
dure in this manual for checks, adjustments,
and replacement of parts.
EAS28470
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 rings
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 strainer
Clogged fuel tank breather hose
Clogged rollover valve
Deteriorated or contaminated fuel
2. Fuel cock
Clogged or damaged fuel hose
3. Carburetor
Deteriorated or contaminated fuel
Clogged pilot jet
Clogged pilot air passage
Sucked-in air
Damaged float
Worn needle valve
Improperly installed needle valve seat
Incorrect fuel level
Improperly installed pilot jet
Clogged starter jet
Faulty starter plunger
Choke valve malfunction
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
Faulty spark plug cap
Wire between terminals broken
4. Ignition coil
Cracked or broken ignition coil body
Broken or shorted primary or secondary
coils
Faulty spark plug lead
5. Ignition system
Faulty CDI unit
Faulty pickup coil
Faulty stator coil
Broken generator rotor woodruff key
6. Switches and wiring
Faulty main switch
Faulty engine stop switch
Broken or shorted wiring
Faulty neutral switch
Faulty start switch
Faulty clutch switch
Improperly grounded circuit
Loose connections
7. Starting system
Faulty starter motor
Faulty starter relay
Faulty starting circuit cut-off relay
Faulty starter clutch