DESCRIPTION
Fuel evaporation control system is designed to prevent fuel vapor from being emitted into the atmosphere. The system consists of a non-vented fuel tank filler cap, expansion tank, charcoal canister, control valve, roll-over valve, switching valve, thermo valve and connecting lines and hoses.
OPERATION
Expanded fuel, caused by high ambient temperatures, is collected in the expansion tank. This fuel is returned to main tank by venting action as fuel is used from main tank.
Fuel vapor produced in main tank passes through a vent line to the charcoal canister where it is stored in activated charcoal. A second vent line, with control valve, connects canister to air cleaner and intake system.
When engine is running, intake vacuum draws fresh air through charcoal canister. This fresh air mixes with fuel vapor and is drawn into intake system where it enters combustion chamber to be burned.
The thermo valve, switching valve and control valve are connected in series to control amount of vapor purge.
The thermo valve opens at coolant temperatures above 136°F (58°C) to apply vacuum to the switching valve. The switching valve receives vacuum when coolant temperature is above 136°F (58°C) and when throttle valve angle is at least 1°. The control valve receives vacuum from a separate vacuum line that is taken from a port below the throttle valve. This allows control valve to vary amount of purging dependent upon throttle angle. These 3 devices, working in conjunction with each other, ensure purging occurs only when coolant temperature exceeds 136°F (58°C) and throttle valve angle is at least 1°.
TESTING
Note. Testing information not available.
MAINTENANCE
Check entire system for leaks, damage, and deterioration every 15,000 miles.
Poses Online