Patent ID: 7441548

Claim:
A fuel supply apparatus comprising: a volumetric chamber that is arranged in a casing of an outboard motor; a low pressure fuel pump that is connected to a fuel tank arranged outside of said casing through fuel piping, and at the same time to said volumetric chamber through an inflow passage so as to supply fuel from said fuel tank to said volumetric chamber; a first one-way valve that is arranged in said inflow passage so as to allow fuel to flow from said low pressure fuel pump to said volumetric chamber; a first return passage that has one end connected to said volumetric chamber and the other end connected to said fuel piping in said casing; a second one-way valve that is arranged in said first return passage so as to allow fuel to flow from said volumetric chamber to said fuel piping; and a high pressure fuel pump that has a fuel pressure holding valve which is opened when a fuel discharge pressure becomes equal to or more than a predetermined value, and supplies the fuel in said volumetric chamber to a high pressure passage connected to a fuel injector unit; wherein said low pressure fuel pump has its discharge flow rate adjusted to be greater than that of said high pressure fuel pump, and surplus fuel accumulating in said volumetric chamber is caused to circulate through said volumetric chamber, said first return passage, said fuel piping and said inflow passage under the action of said low pressure fuel pump and said first and second one-way valves.