Air/Fuel Controls

In 4 and 6 cylinder applications, the MCU provides a pulsed voltage signal which operates a fuel control solenoid/vacuum regulator (4 Cyl.) or a fuel control solenoid (6 Cyl.). On 4 cylinder engines, the vacuum is applied to a mixture control diaphragm in the carburetor, while 6 cylinder engines are directly operated by the solenoid which is a part of the carburetor.

On V8 engines, the MCU provides current to a feedback motor in the carburetor, also known as a Feedback Carburetor Actuator (FBCA). This motor extends and retracts a shaft which alters a bleed-air orifice in the carburetor.