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A positive displacement type pump for use in a fuel system of an internal combustion engine having a pump housing that includes a pump chamber and a vapor vent valve to allow vapor to flow out of the pump chamber. The vent valve includes a valve seat, a valve and a spring biasing the valve away from

A positive displacement type pump for use in a fuel system of an internal combustion engine having a pump housing that includes a pump chamber and a vapor vent valve to allow vapor to flow out of the pump chamber. The vent valve includes a valve seat, a valve and a spring biasing the valve away from the valve seat. During pump operation, the liquid fuel flow pressure within the pump chamber is great enough to seat the valve and prevent fuel from escaping through the vapor vent valve. However, if the internal pressure drops due to a loss of pumping pressure caused by the ingestion of air or vapors, the vent valve automatically opens to allow vapor or air flow through the pump with a resultant cooling effect on the pump assembly.

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A pump housing for a fuel pump comprising: a fuel inlet portion having an inlet port, a fuel outlet portion having an outlet port, a pump chamber disposed between said inlet portion and said outlet portion enclosing a pumping mechanism coupled to an electric motor to pump fuel from said inlet port t

A pump housing for a fuel pump comprising: a fuel inlet portion having an inlet port, a fuel outlet portion having an outlet port, a pump chamber disposed between said inlet portion and said outlet portion enclosing a pumping mechanism coupled to an electric motor to pump fuel from said inlet port to said outlet port; and venting means associated with said pump housing comprising a vent opening and a resiliently biased shuttle valve in said opening responsive to vapor pressure below normal pump pressure for venting vapor within said pump chamber to an ambient environment and responsive to the pressure of liquid fuel to close said opening, said venting means including a valve chamber having: (a) a first valve seat at one end open to atmosphere and a valve stop having a second seat at the other end of said valve chamber, said second seat having an effective opening substantially larger than the effective opening of said first seat, (b) a shuttle valve in said valve chamber having a head end at the end of said valve chamber adjacent said second seat, said head end being larger than said effective opening of said second seat to close said shuttle valve against said second seat, said shuttle valve having a second end opposite said head end of smaller dimension to cooperate with said first seat when moved against said first seat, and (c) a light spring seated at a first end in said valve chamber adjacent said first seat, positioned around said second smaller end of said valve and seated at a second end of said spring against said head end of said valve, whereby light vapor pressure in said pump will act through said second seat against the larger head end of said valve to move said valve sufficiently to pass said vapor to said first seat without closing said first seat, and the presence of liquid fuel under operating pressure will shuttle said valve to close said first seat.