Sym ATTILA RS-21 EFi 150 Service Manual page 19

1. General Information/Trouble Diagnosis
C. Engine runs sluggish (especially in low speed and idling)
Check and adjustment
Check ignition timing
(using ignition lamp)
Normal
Check If air sucked through
throttle valve gasket
No air sucked
Remove spark plug, install
spark plug into spark plug
cap and perform spark test
against engine ground
Good spark
D. Engine runs sluggish (High speed)
Check and adjustment
Check ignition timing
Normal
Check for fuel supplying
system in fuel pump
Good
Check if fuel injector is
clogged
No clogged
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Fault condition
Abnormal
Air sucked
Poor spark
Fault condition
Abnormal
Poor
Clogged
Probable causes
1. Incorrect ignition timing (malfunction of
ECU or AC alternator)
1. Heat insulation gasket to damage
2. Throttle valve lock loose
3. Intake gasket to damage
4. By-pass hose crack
1. Spark plug fouled
2. Malfunction of ECU
3. Malfunction of AC generator
4. Malfunction of ignition coil
5. Open or short circuit in spark plug
leads
6. Malfunction of main switch
Probable causes
1. Malfunction of ECU
2. Malfunction of AC alternator
1. Insufficient fuel in fuel tank
2. Fuel line clogged
3. Restricted fuel tank EEC line
1. Replace fuel injector