Engine Won’t Start Or Hard To Start; Troubleshooting - DAELIM Besbi SC125 Service Manual

19. TROUBLESHOOTING

ENGINE WON'T START OR HARD TO START
ENGINE STALLS, HARD TO START, ROUGH IDLING
POOR PERFORMANCE AT LOW SPEED AND IDLING
POOR OPERATION
ENGINE WON'T START OR HARD TO START
Open the drain screw, and check fuel
flow to the carburetor.
Fuel is supplied
Check the spark plug.
Good spark
Measure the cylinder compression.
Compression normal
Start the engine in the following
procedure.
Engine won't start.
Remove the spark plug, and recheck it.
Dry spark plug
Restart the engine in the following
procedure.
Engine starts
Completion
Fuel not supplied
to the carburetor.
Weak or no spark.
Low or no cylinder
compression.
Engine starts but
stops immediately.
Spark plug wet.
Engine won't start.
TROUBLESHOOTING
20-1
20-2
20-3
20-4
CAUSE OF TROUBLE
No fuel to fuel tank.
Disconnected or damaged fuel pump
negative pressure tube.
Clogged fuel tube.
Clogged float valve.
Clogged fuel strainer.
Clogged fuel tank cap.
Fuel pump malfunction.
Faulty spark plug.
Contaminated spark plug.
Faulty A.C. generator.
Disconnected or shorted high
tension cord.
Disconnected or shorted ignition coil
wire.
faulty ignition switch.
Faulty CDI unit.
Seized piston ring.
Faulty valve clearance adjustment.
Worn cylinder or piston ring.
Leaking cylinder gasket.
Warped or cracked cylinder head or
cylinder.
Carbon deposited on spark plug.
Idle speed misadjusted.
Faulty ignition timing.
Clogged air cleaner.
Lean fuel mixture.
Flooded carburetor.
Throttle valve excessively opened.
Contaminated or clogged air cleaner.
Rich fuel mixture.
Recheck the engine.
19-1