General Information

Fig. 13 Evaporative emission control system.:

22R ENGINES

When the vehicle is stopped or running at low speeds, the speed sensor transmits a signal to the computer which will not allow the vacuum switching valve (VSV) to open until the vehicle has reached a predetermined speed. Any fuel vapors will now be absorbed by and stored in the charcoal canister. When the vehicle has reached the predetermined speed, the speed sensor sends a signal to the computer, which in turns activates the VSV to allow the fuel vapors to be drawn from the charcoal canister into the intake manifold, Fig. 13.
An outer vent control valve is used to vent vapors from the carburetor float bowl to the charcoal canister. When the ignition switch is in the off position, the vent control valve is open allowing vapors from the float bowl to be vented to the canister. When the ignition switch is on, the vent control valve is closed.
A thermo switch is used, which responds to coolant temperature when the ignition switch is turned on.




2S-E, 3S-FE, 3S-GE, 4A-GE, 4A-GEC, 4A-GEL, 4A-GELC, 5M-GE, 7M-GE, 7M-GTE & 22R-E ENGINES

The system for these models includes a bi-metal vacuum switching valve which responds to coolant temperature. When temperature is below 95°F, the BVSV is closed and vapors are stored in the charcoal canister. At temperatures above 129°F, with throttle valve opening positioned below purge port, No. 1 check valve is closed, trapping vapors in canister. When position of throttle valve opening is above purge port, vapors are led into the air intake chamber to be burned during combustion, refer to Figs.

Fig. 14 Evaporative emission control system.:

Fig. 14

Fig. 15 Evaporative emission control system.:

Fig. 15

Fig. 16 Evaporative emission control system.:

Fig. 16

Fig. 17 Evaporative emission control system.:

Fig. 17

Fig. 18 Evaporative emission control system.:

Fig. 18