Abstract: A sensor detects the flow rate of fuel returned from an internal combustion engine to a fuel tank to control a pump motor in such a manner that an appropriate amount of fuel is supplied from the pump to the engine.

Abstract: A filter device for a fuel tank comprises an upper wall for supporting in position a tubular member such as a fuel line or a pump casing, a bottom wall disposed at a distance from the upper wall, and a cylindrical wall supporting in position a mesh encircling the space intervening between the upper wall and the bottom wall. The cylindrical wall and either the upper wall or the bottom wall are integrally molded of a plastic material in one integral part, the bottom wall or the upper wall is molded separately of a plastic material in a separate part to be fitted to the free end of the cylindrical wall in the one integral part, one of the two parts which has an outer fitting peripheral wall surface is formed of a plastic material having a smaller rate of dimensional change, and the other part which has an inner fitting peripheral wall surface is formed of a plastic material having a larger rate of dimensional change.

Abstract: A device for pumping fluid includes a main pump device and an auxiliary device integrally fixed thereto. The auxiliary device can function as a damper, cut-off valve, check valve and relief valve. The auxiliary device includes a first and second room separated by a diaphragm. The first room is connected to the fuel supply passage of the main pump device. One end of the outlet passage of the auxiliary device is connected to the first room by way of a valve mechanism consisting of a valve body and valve seat. The valve body is actuated by deforming of the diaphragm in response to the change of the fluid pressure within the first room. A relief passage is formed in the valve body to connect the first room with the second room. A relief valve such as a ball valve is placed in cooperation with the relief passage.