Sym PA12B - Page 225

14. Emission Control System
14-6
3. Service Points/Trouble Diagnosis:
Diesel
a. Malfunction of air inject cut valve (AICV).
b. System hose leakage.
c. abnormal ignition timing.
d. lean mixture gas.
e. abnormal fuel supply.
Rich Exhaust Gas:
a. plugged air-jet by dirty carburetor.
b. poor adjustment of air adjustment screw.
c. poor reed valve.
d. System hose leakage or plugged.
Noise:
a. System hose leakage.
b. Loosen secondary air injection filter.
c. Loosen secondary air injection filter hose.
4. AI System Service methods:
a. Visual check:
y Check reed valve, air cut-off valve, secondary air cleaner for outside damages.
y Check metal pipes and hoses for breakage and cracks.
b. Leak test:
y Plug the hose leading to reed valve.
y Remove the hose of connection to air injection cut valve. Connect a T-type hose connector,
pressure gauge and pressure source as shown above.
y With engine stopped, apply 1.0kg/cm2 pressure to inlet and then plug it. There should be no
leakage.
To engine vacuum
source
To reed valve
(R/V)
Air inject cut valve (AICV)
Pressure gauge
Secondary air injection filter
(A.I.A.C.)
Pressure source
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