Troubleshooting; Starting Failure/ Hard Starting Engine; Fuel System - Yamaha CS50 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 FAILURE/ HARD STARTING
ENGINE
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
Piston(s) and piston ring(s)
• Improperly installed piston ring
• Damaged, worn or fatigued piston ring
• Seized piston ring
• Seized or damaged piston
Air filter
• Improperly installed air filter
• Clogged air filter element
Crankcase and crankshaft
• Improperly assembled crankcase
• Seized crankshaft
STARTING FAILURE/HARD STARTING

TROUBLESHOOTING

FUEL SYSTEM

Fuel tank
• Empty fuel tank
• Clogged fuel tank cap breather hole
• Deteriorated or contaminated fuel
• Clogged or damaged fuel hose
Fuel pump
• Faulty fuel pump
• Faulty fuel pump relay
• Damaged vacuum hose
• Improperly routed hose
Carburetor(s)
• 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 adjusted pilot air screw
• Improperly installed pilot jet
• Clogged starter jet
• Clogged emulsion tube
Autochoke unit
• Faulty starter plunger
• Improperly adjusted starter cable
• Faulty ignitor unit
• Faulty thermo switch
9-1
TRBL
SHTG