High Altitude Compensation System: Operation
Solenoid valve opens a passage between air cleaner and carburetor. Fresh air will then pass through 3 main metering orifices and be supplied to idle and off idle systems in addition to primary and secondary main metering systems. The high altitude idle-up solenoid valve will open a passage to a port located downstream of throttle valve. Additional air/fuel mixture will be supplied to engine, permitting stable idle RPM at high altitude. See Fig 1 .