Fuel Delivery and Air Induction: Description and Operation

Fig. 3 Model 2150 feedback fuel control:

Feedback fuel control utilizes a pulsing solenoid, Fig. 3, to introduce fresh air from the air cleaner into the idle and main system vacuum passages to lean the air/fuel mixture from the maximum rich condition (0% duty cycle, solenoid closed) to the maximum lean condition (100% duty cycle, solenoid open). The solenoid operates under control of the EEC system.