14-11
HRX217HYA • HRX217HZA OPERATION
4. FUEL TANK CAP
EVAPORATIVE EMISSION CONTROL SYSTEM
These engines have an EVAPORATIVE EMISSION CONTROL CANISTER built into the fuel tank cap to prevent the
escape of gasoline vapors into the atmosphere. The cap also contains a ratchetting mechanism that will click when
the cap is properly sealed and prevent the cap from being overtightened.
PRINCIPLE
CHARGING:
Gasoline vapor produced in the fuel tank at high ambient
temperature is absorbed and stored by the charcoal in the
canister, which is built into the fuel tank cap.
PURGING:
When the pressure in the fuel tank decreases because of low
ambient temperature or consumption of gasoline, the air drawn
through the canister releases the stored gasoline vapor from the
charcoal. The released gasoline vapor returns to the fuel tank.