Evaporative Emissions System: Description and Operation

Fig. 60 Evaporative Emission Control System (std):

STD

The evaporative controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The system consists of the following components:

1. Charcoal Canister
A canister for the temporary storage of the fuel vapor until the fuel vapor can be purged from the canister into the engine and burned.

2. Vapor Purge Control System
Canister purging is accomplished by drawing fresh air through the canister and into a port on the throttle body. The ported vacuum is controlled by the purge control diaphragm valve and the purge cut-off solenoid valve.

Operating conditions:

Purge cut-off solenoid remains off longer than 10 seconds after engine start until:
coolant temperature rises above 80°C (176°F) and the throttle valve is not fully closed.

3. Fuel Tank Vapor Control System
When fuel vapor pressure in the fuel tank is higher than the set value of the two-way valve, the valve opens and regulates the flow of fuel vapor to the canister.

Fig. 61 Evaporative Emission Control System (HF Si):

HF AND Si

The evaporative controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The system consists of the following components:

1. Charcoal Canister
A canister for the temporary storage of the fuel vapor until the fuel vapor can be purged from the canister into the engine and burned.

2. Vapor Purge Control System
Canister purging is accomplished by drawing fresh air through the canister and into a port on the throttle body. The ported vacuum is controlled by the purge control diaphragm valve and the purge cut-off solenoid valve.

Operating conditions:

HF

Purge cut-off solenoid remains off longer than 5 seconds after engine start until:
Coolant temperature rises above 40°C (104°F)

Si

Purge cut-off solenoid remains off longer than 5 seconds after engine start until:
coolant temperature rises above 135°F
3. Fuel Tank Vapor Control System
When fuel vapor pressure in the fuel tank is higher than the set value of the two-way valve, the valve opens and regulates the flow of fuel vapor to the canister.