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A valve assembly for a tank of a vehicle and a method of creating a vacuum are disclosed. A valve body defines a cavity and an outlet in fluid communication with the cavity for venting the tank. The assembly includes a seat disposed in the cavity of the valve body. The seat separates the cavity into

A valve assembly for a tank of a vehicle and a method of creating a vacuum are disclosed. A valve body defines a cavity and an outlet in fluid communication with the cavity for venting the tank. The assembly includes a seat disposed in the cavity of the valve body. The seat separates the cavity into first and second cavity portions. The seat defines an aperture to provide fluid communication between the first and second cavity portions. The assembly includes a cover device disposed between the seat and the outlet. The cover device defines at least one hole therethrough. The cover device is movable between a rest position engaging the seat to minimize fluid communication between the aperture and the hole and an actuated position spaced from the seat to increase fluid communication between the aperture and the hole when a vacuum is created in the first cavity portion.

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1. A valve assembly for a tank of a vehicle, the assembly comprising: a valve body adapted to be attached to the tank, with the valve body defining a cavity along a longitudinal axis and defining an outlet in fluid communication with the cavity for venting the tank;a seat disposed in the cavity of t

1. A valve assembly for a tank of a vehicle, the assembly comprising: a valve body adapted to be attached to the tank, with the valve body defining a cavity along a longitudinal axis and defining an outlet in fluid communication with the cavity for venting the tank;a seat disposed in the cavity of the valve body and separating the cavity into a first cavity portion and a second cavity portion, with the seat defining an aperture along the longitudinal axis to provide fluid communication between the first and second cavity portions; anda cover device disposed between the seat and the outlet, with the cover device defining at least one hole through the cover device such that fluid communication between the aperture and the outlet is through the hole of the cover device, and with the cover device movable between a rest position engaging the seat to minimize fluid communication between the aperture and the hole, and an actuated position spaced from the seat to increase fluid communication between the aperture and the hole when a vacuum is created in the first cavity portion;wherein the cover device separates the first cavity portion into a first pocket and a second pocket, and wherein the aperture is in direct fluid communication with the first pocket when the cover device is in the actuated position, and the outlet is in direct fluid communication with the second pocket when the cover device is in the rest position and the actuated position. 2. An assembly as set forth in claim 1 wherein the cover device includes a plate movable between the rest and actuated positions to selectively engage the seat, with the plate defining the at least one hole. 3. An assembly as set forth in claim 2 wherein the cover device includes a diaphragm attached to the plate and the valve body such that the plate and the diaphragm cooperate to cover the seat, with the diaphragm at least partially movable with the plate between the rest and actuated positions. 4. An assembly as set forth in claim 2 wherein the at least one hole is further defined as a plurality of holes spaced from each other, with the plate defining the holes. 5. An assembly as set forth in claim 3 wherein the seat includes a first surface facing the first cavity portion and a second surface facing the second cavity portion, with the plate selectively engaging the first surface of the seat, and with the diaphragm spaced from the first surface when the plate is in the rest and actuated positions. 6. An assembly as set forth in claim 5 wherein the first surface of the seat defines a notch adjacent to the aperture to provide fluid communication between the first and second cavity portions to substantially equalize small pressure differences between the first and second cavity portions when the cover device is in the rest position. 7. An assembly as set forth in claim 6 wherein the at least one hole is further defined as a plurality of holes spaced from each other and wherein the plate includes a first side and a second side opposing each other, with the first and second sides of the plate defining the holes therethrough, and wherein the second side of the plate defines a groove in fluid communication with one of the holes and the notch, with the groove disposed between the one of the holes and the first surface of the seat such that the one of the holes is spaced from the first surface of the seat when the plate is in the rest position. 8. An assembly as set forth in claim 1 wherein the cover device includes a plate, and the plate includes a first side and a second side opposing each other and wherein the seat is further defined as a first seat and the plate includes a second seat extending from the first side facing away from the first seat, and further including a biasing member disposed in the first cavity portion and engaging the valve body and the first side of the plate, with the second seat surrounding the biasing member to position the biasing member relative to the plate. 9. An assembly as set forth in claim 1 wherein the first and second cavity portions have a substantially equal first pressure when the cover device is in the rest position before the vacuum has been created, and the first cavity portion obtains a second pressure less than the first pressure of the second cavity portion when the vacuum is created in the first cavity portion by fluid being removed from the first cavity portion through the outlet while the cover device is in the rest position which causes the cover device to move to the actuated position such that fluid flows from the second cavity portion through the first cavity portion and out the outlet. 10. An assembly as set forth in claim 1 further including a float disposed in the second cavity portion of the valve body, with the float movable along the longitudinal axis between a first position and a second position relative to the valve body in response to a fluid level inside the tank, and further including a sealing member coupled to the float, with the sealing member spaced from the seat when the float is in the first position and the sealing member engages the seat when the float is in the second position, and with the float being in the first position when the vacuum is created such that fluid flows from the second cavity portion through the aperture, the first cavity portion, and the hole, and out the outlet. 11. An assembly as set forth in claim 1 wherein the vacuum is created by expelling gaseous fluid out of the outlet when the cover device is in the rest position which causes a pressure difference between the first cavity portion and the second cavity portion, and the pressure difference causes the cover device to move to the actuated position such that the gaseous fluid flows from the second cavity portion through the cover device and out the outlet. 12. An assembly as set forth in claim 1 wherein the aperture of the seat and the outlet of the valve body are spaced apart relative to opposite sides of the cover device relative to a flow of gaseous fluid. 13. An assembly as set forth in claim 1 wherein the cover device includes a plate and a diaphragm attached to each other, with the plate formed of a material different from the diaphragm. 14. An assembly as set forth in claim 1 wherein fluid communication between the first and second pockets is through the hole, and wherein the cover device includes a pair of sides, with one of the sides defining a boundary of the first pocket of the first cavity portion and another one of the sides defining a boundary of the second pocket of the first cavity portion, and wherein the aperture is separated from the outlet by the sides of the cover device. 15. A valve assembly for a tank of a vehicle, the assembly comprising: a valve body adapted to be attached to the tank, with the valve body defining a cavity along a longitudinal axis and defining an outlet in fluid communication with the cavity for venting the tank;a seat disposed in the cavity of the valve body and separating the cavity into a first cavity portion and a second cavity portion, with the seat including a platform defining an aperture along the longitudinal axis to provide fluid communication between the first and second cavity portions; anda cover device disposed between the seat and the outlet, with the cover device defining at least one hole through the cover device, and with the cover device movable between a rest position engaging the platform to minimize fluid communication between the aperture and the hole and an actuated position spaced from the platform to increase fluid communication between the aperture and the hole when a vacuum is created in the first cavity portion;wherein the first and second cavity portions have a substantially equal first pressure when the cover device is in the rest position before the vacuum has been created, and the first cavity portion obtains a second pressure less than the first pressure of the second cavity portion when the vacuum is created in the first cavity portion by gaseous fluid being removed from the first cavity portion through the outlet while the cover device is in the rest position which causes the cover device to move to the actuated position to increase fluid communication between the first and second cavity portions. 16. An assembly as set forth in claim 15 wherein the cover device includes a plate movable between the rest and actuated positions to selectively engage the platform, with the plate defining the at least one hole, and wherein the cover device includes a diaphragm attached to the plate and the valve body such that the plate and the diaphragm cooperate to cover the platform, with the diaphragm at least partially movable with the plate between the rest and actuated positions. 17. An assembly as set forth in claim 16 wherein the platform includes a first surface facing the first cavity portion and a second surface facing the second cavity portion, with the plate selectively engaging the first surface of the platform, with the diaphragm being spaced from the first surface when the plate is in the rest and actuated positions. 18. An assembly as set forth in claim 15 wherein the seat includes a protrusion extending from the platform into the second cavity portion, with the protrusion further defining the aperture, and further including a float disposed in the second cavity portion of the valve body, with the float movable along the longitudinal axis between a first position and a second position relative to the valve body in response to a fluid level inside the tank, and further including a sealing member coupled to the float, with the sealing member spaced from the protrusion when the float is in the first position and the sealing member engages the protrusion when the float is in the second position, and with the float being in the first position when the vacuum is created such that gaseous fluid flows from the second cavity portion through the aperture, the first cavity portion, and the hole, and out the outlet. 19. A method of creating a vacuum in a tank of a vehicle when performing a diagnostic test, the method comprising: providing a valve body adapted to be attached to the tank, with the valve body including a first cavity portion and a second cavity portion separated by a seat;minimizing flow of gaseous fluid between a hole in a cover device and an aperture of the seat when the cover device is in a rest position engaging the seat;removing gaseous fluid from the first cavity portion of the valve body out through an outlet of the valve body while the cover device is in the rest position to create the vacuum in the first cavity portion and a pressure difference between the first and second cavity portions;moving the cover device to an actuated position spaced from the seat in response to the vacuum creating the pressure difference between the first and second cavity portions; andincreasing flow of the gaseous fluid between the hole in the cover device and the aperture of the seat when the cover device is in the actuated position to increase flow of the gaseous fluid between the first and second cavity portions. 20. A method as set forth in claim 19 wherein the aperture of the seat and the outlet of the valve body are spaced apart relative to opposite sides of the cover device, and wherein removing the gaseous fluid includes expelling the gaseous fluid out of the outlet and from the first cavity portion relative to one side of the cover device while the cover device is in the rest position.