Starting Failure/Hard Starting; Engine; Fuel System; Electrical Systems - Yamaha XF50W Service Manual

EAS00845
NOTE:
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 procedure in this manual
for checks, adjustments, and replacement of parts.
STARTING
STARTING

ENGINE

Cylinder and cylinder head
8Loose spark plug
8Loose cylinder head or cylinder
8Damaged cylinder head gasket
8Damaged cylinder gasket
8Worn or damaged cylinder
8Incorrect valve clearance
8Improperly sealed valve
8Incorrect valve-to-valve-seat contact
8Incorrect valve timing
8Faulty valve spring
8Seized valve
Piston and piston ring
8Improperly installed piston ring
8Damaged, worn or fatigued piston ring
8Seized piston ring
8Seized or damaged piston
Air filter
8Improperly installed air filter
8Clogged air filter element
Crankcase and crankshaft
8Improperly assembled crankcase
8Seized crankshaft

FUEL SYSTEM

Fuel tank
8Empty fuel tank
8Clogged fuel tank cap breather hole
8Deteriorated or contaminated fuel
8Clogged or damaged fuel hose
Fuel pump
8Faulty fuel pump
8Improperly routed hose

STARTING FAILURE/HARD STARTING

TROUBLESHOOTING
FAILURE/HARD
Throttle body
8Deteriorated or contaminated fuel
8Sucked-in air

ELECTRICAL SYSTEMS

Battery
8Discharged battery
8Faulty battery
Fuse
8Blown, damaged or incorrect fuse
8Improperly installed fuse
Spark plug
8Incorrect spark plug gap
8Incorrect spark plug heat range
8Fouled spark plug
8Worn or damaged electrode
8Worn or damaged insulator
8Faulty spark plug cap
Ignition coil
8Cracked or broken ignition coil body
8Broken or shorted primary or secondary
coil
8Faulty spark plug lead
Ignition system
8Faulty ECU
8Faulty crankshaft position sensor
8Broken AC magneto rotor woodruff key
Switches and wiring
8Faulty main switch
8Faulty engine stop switch
8Broken or shorted wiring
8Faulty front, rear or both brake light
switches
8Faulty start switch
8Faulty sidestand switch(optional)
8Improperly grounded circuit
8Loose connections
9-1
TRBL Q
SHTGl •