Air Injection System: Operation

The air pump is a low pressure unit, belt driven by the engine, which uses vanes on its drive pulley as a centrifugal filter. The air delivery line is connected to the check valve. The check valve prevents hot exhaust gases from flowing out through the delivery line and pump in case the pump fails or exhaust gas pressure becomes excessive.

A relief valve, mounted on the air pump on Strada and X1/9 or on the air cleaner on Brava and Spider, is used to vent excess pump pressure. See Figure and Figure. Pump output which passes through the check valve enters the cylinder head passages and is delivered to the exhaust ports.