Fuel injection device

A fuel injection device, comprising:

• a fuel pump that pressurizes fuel;
• a solenoid valve that injects the pressurized fuel into an intake passage of an engine;
• a high-pressure fuel passage that extends from the fuel pump, has in a region thereof a constant pressure chamber that adjusts the fuel to a predetermined pressure, and leads to the solenoid valve;
• and
• a fuel return passage that extends from the constant pressure chamber, has a priming pump in a region thereof, and is connected to a fuel return pipe;
• wherein, with the constant pressure chamber, a top wall of an upper portion space thereof is at a position above an opening portion of the high-pressure fuel passage heading toward the solenoid valve, the fuel return passage is opened at the upper portion space at a position above the opening portion of the high-pressure fuel passage, and a gas accumulated in the constant pressure chamber is exhausted from the upper portion space to a fuel tank side via the fuel return passage;
• wherein, the priming pump is configured from two check valves connected from a side portion at a predetermined interval in a region of the fuel return passage and a suction and extrusion means of a cup shape made of an elastic material that covers an opening side of the two check valves and forms a pump chamber, a bypass path is formed between the two check valves, a non-return valve is provided that restricts passage of a fluid in the bypass path to only be in a fuel return direction, the non-return valve closes when the priming pump is used so as to not pass the fluid through, and the non-return valve opens when the fuel is returned and when the gas is exhausted so as to pass the fluid through.