Starting Failures; Incorrect Engine Idling Speed - Yamaha FZ8NA Service Manual

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.
EAS30410

STARTING FAILURES

Engine
1. Cylinder(s) and cylinder head(s)
• 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(s) 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 cap breather hole
• Deteriorated or contaminated fuel
• Clogged or damaged fuel hose
2. Fuel pump
• Faulty fuel pump
• Faulty fuel pump relay
3. Throttle body (-ies)
• Deteriorated or contaminated fuel
• Sucked-in air
TROUBLESHOOTING
Electrical system
1. Battery
• Discharged battery
• Faulty battery
2. Fuse(s)
• Blown, damaged or incorrect fuse
• Improperly installed fuse
3. Spark plug(s)
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
4. Ignition coil(s)
• Cracked or broken ignition coil body
• Broken or shorted primary or secondary
coils
5. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Faulty cylinder identification sensor
• Broken pickup rotor straight key
6. Switches and wiring
• Faulty main switch
• Faulty engine stop switch
• Broken or shorted wiring
• Faulty neutral switch
• Faulty start switch
• Faulty sidestand 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
EAS30440

INCORRECT ENGINE IDLING SPEED

Engine
1. Cylinder(s) and cylinder head(s)
• Incorrect valve clearance
• Damaged valve train components
2. Air filter
• Clogged air filter element
Fuel system
1. Throttle body (-ies)
• Damaged or loose throttle body joint
• Improperly synchronized throttle bodies
• Improperly adjusted engine idling speed
(idle adjusting screw)
9-1