Electrical Systems; Incorrect Engine Idling Speed; Engine; Fuel System - Yamaha YP400T, YP400V, YP400W Service Manual

ELECTRICAL SYSTEMS

Battery
• Discharged battery
• Faulty battery
Fuse(s)
• Blown, damaged or incorrect fuse
• Improperly installed fuse
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
Ignition coil
• Cracked or broken ignition coil body
• Broken or shorted primary or secondary
coils
• Faulty spark plug lead
EAS00847

INCORRECT ENGINE IDLING SPEED

ENGINE

Cylinder and cylinder head
• Incorrect valve clearance
• Damaged valve train components
Air filter
• Clogged air filter element

FUEL SYSTEM

Throttle body
• Damaged or loose throttle body joint
• Improper throttle cable free play
• Flooded throttle body
• Faulty air induction system
STARTING FAILURE/HARD STARTING/
INCORRECT ENGINE IDLING SPEED
Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
Switches and wiring
• Faulty main switch
• Faulty engine stop switch
• Broken or shorted wiring
• Faulty front, rear or both brake light
switches
• Faulty start switch
• Faulty sidestand switch
• Improperly grounded circuit
• Loose connections
Starting system
• Faulty starter motor
• Faulty starter relay
• Faulty starting circuit cut-off relay
• Faulty starter clutch
ELECTRICAL SYSTEMS
Battery
• Discharged battery
• Faulty battery
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
Ignition coil
• Faulty spark plug lead
Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
9 - 2
TRBL
SHTG