Fuel supply device

A fuel supply device comprising:

• a fuel pump;
• a filter case that receives a fuel filter in its receiving chamber, wherein the fuel supply device filters fuel, which is pressure-sent from an interior of a fuel tank by the fuel pump, through the fuel filter and supplies fuel to an internal-combustion engine;
• a fuel passage that is provided in the filter case and includes a communication port, which communicates with the receiving chamber on a downstream side of the fuel filter, wherein fuel flows from the communication port through the fuel passage;
• a discharge passage that is provided in the filter case and discharges the fuel flowing through the fuel passage into the internal-combustion engine;
• and
• a spring-urged type residual pressure holding valve that is provided at the filter case and holds a pressure of fuel in the receiving chamber when the fuel pump is stopped, wherein:
• the residual pressure holding valve includes a valve element, which opens the residual pressure holding valve against spring reaction force when the fuel pump is actuated;
• the communication port opens at a shifted position of the fuel passage that is positionally shifted from the residual pressure holding valve toward the discharge passage;
• the fuel passage includes:
• an outside passage part through which fuel flows from the communication port toward the discharge passage;
• and
• an inside passage part that throttles a flow of fuel flowing from the communication port toward the residual pressure holding valve more than the outside passage part;
• and
• when a passage cross-sectional area of the inside passage part is converted into a passage cross-sectional area of a circular pipe, D which is a passage diameter of the circular pipe, and L which is a length of the inside passage part satisfy a relational expression of L/D≧3.