Starting Failure/Hard Starting; Fuel System; Electrical System - Yamaha YQ50 Service Manual

NOTE:
The following troubleshooting does not cover all the possible causes of trouble. It should be helpful,
however, as a guide to troubleshooting. Refer to the relative procedure in this manual for inspection,
adjustment and replacement of parts.

STARTING FAILURE/HARD STARTING

FUEL SYSTEM

Fuel tank
• Empty
• Clogged fuel filter
• Deteriorated fuel or fuel containing water or
foreign material
• Clogged fuel tank cap
Fuel cock
• Clogged fuel hose
Air cleaner
• Clogged air filter

ELECTRICAL SYSTEM

Spark plug
• Improper plug gap
• Worm electrodes
• Wire between terminals broken
• Improper heat range
• Faulty spark plug cap
Ignition coil
• Broken or shorted primary/secondary
• Faulty spark plug lead
• Broken body
STARTING FAILURE/HARD STARTING
TROUBLESHOOTING
Carburetor
• Deteriorated fuel, fuel containing water or
foreign material
• Clogged pilot jet
• Clogged pilot air passage
• Sucked-in air
• Deformed float
• Groove-worm needle valve
• Improperly sealed valve seat
• Improperly adjusted fuel level
• Improperly set pilot jet
• Clogged starter jet
• Starter plunger malfunction
• Improperly adjusted pilot air screw
CDI unit system
• Faulty CDI unit
• Faulty source coil
• Faulty pick-up coil
Switches and wiring
• Faulty main switch
• Broken or shorted wiring
9-1
TRBL
SHTG