Fuel pump having plunger and fuel supply system using the same

A fuel supply system including a fuel pump comprising:

• a pump housing that has a compression chamber and at least one mount hole;
• a plunger that is movable in the pump housing, the plunger being adapted to pressurizing fuel in the compression chamber;
• a delivery valve that communicates the compression chamber with a downstream of the delivery valve when pressure in the compression chamber is equal to or greater than a threshold;
• and
• at least one fluid component that is adapted to communicating an upstream of the compression chamber with a downstream of the compression chamber,
• wherein at least one of the plunger, the delivery valve, and the at least one of fluid component is provided to the at least one mount hole of the pump housing,
• the at least one of the plunger, the delivery valve, and the at least one of fluid component defines at least one clearance with respect to the at least one mount hole, and
• the at least one clearance communicates the downstream of the delivery valve with the upstream of the compression chamber at least in a condition where fuel pressure in the compression chamber is less than the threshold.

A fuel supply system including a fuel pump comprising:

• a pump housing that has a compression chamber and a mount hole;
• a plunger that is movable in the pump housing, the plunger being adapted to pressurizing fuel in the compression chamber;
• a delivery valve that communicates the compression chamber with a downstream of the delivery valve when pressure in the compression chamber is equal to or greater than a threshold;
• and
• wherein the delivery valve is provided to the mount hole of the pump housing,
• the delivery valve defines a clearance with respect to the mount hole, and
• the clearance communicates the downstream of the delivery valve with the upstream of the compression chamber at least in a condition where fuel pressure in the compression chamber is less than the threshold.

A fuel supply system including a fuel pump comprising:

• a pump housing that has a compression chamber;
• a plunger that is movable in the pump housing to pressurize fuel in the compression chamber;
• and
• a delivery valve that communicates the compression chamber with a downstream of the delivery valve when pressure in the compression chamber is equal to or greater than a threshold,
• wherein the pump housing at least partially defines at least one clearance that communicates the downstream of the delivery valve with an upstream of the compression chamber at least in a condition where fuel pressure in the compression chamber is less than the threshold.