| 摘要 |
A method of operating a fuel tank isolation valve and a canister vent valve. The fuel tank isolation valve has a first port, a second port, an electric actuator, and a valve body. The first port is in fluid communication with a fuel vapor collection canister. The second port is in fluid communication with a fuel tank. The electric actuator moves the valve body to control fluid communication between the first and second ports. And the canister vent valve controls ambient fluid flow with respect to the fuel vapor collection canister. The method includes supplying a first electric signal to the electric actuator such that the valve body permits substantially unrestricted fuel vapor flow between the first and second ports, supplying a second electric signal to the electric actuator such that the valve body substantially prevents fuel vapor flow between the first and second ports, supplying a third electric signal to the electric actuator such that the valve body provides restricted fuel vapor flow between the first and second ports, and supplying a fourth electric signal to the canister vent valve to permit ambient fluid flow into the fuel vapor collection canister. The supplying the fourth electric signal is coincident with the supplying the second electric signal.
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