Mixture Control Solenoid: Description and Operation

Duty Solenoid Valve:

PURPOSE
Controls A/F mixture in both the slow (idle) and main (cruise) circuits of the carburetor.

LOCATION
In the carburetor body.

OPERATION
The duty solenoid valve is controlled by a signal from the EFC control unit. The signal controls the duration ratio of current flow (duty value). The valve is equipped with a control air bleed and a control fuel jet. When current is sent to the valve, a plunger inside moves downward, opening the port to the control air bleed and closing the port to the control fuel jet. With no current, a spring moves the plunger upward to close the port to the control air bleed and open the port to the control fuel jet. These ports are routed to both the slow and main ports on the primary side of the carburetor. The air/fuel ratio varies with the duration of current flow (duty value) through the duty solenoid valve.