Air Injection: Description and Operation

Fig. 79 Secondary air supply system.:

This system, Fig.79, is designed to improve emission control performance by supplying fresh air from air cleaner into exhaust manifold through the air suction valve.
On 1984 models, when carburetor vacuum is below set value of vacuum switch and vacuum switch is turned On, the air suction control solenoid valve is open and manifold vacuum is applied to air suction diaphragm valve. Fresh air enters into the exhaust manifold makes air suction reed valve open.
On all models, an air bleed valve is used to prevent overheating in the exhaust system. When intake air temperature rises excessively, the air bleed valve opens and manifold vacuum, which would normally be applied to air suction diaphragm valve, is bled off. This closes the secondary air passage.