Asymmetrical orifice for bypass control

A clean fuel module (CFM) for providing fuel from a fuel reservoir to a fuel transfer pump in a machine having an internal combustion engine, the clean fuel module comprising:

• a CFM bypass pump having a bypass pump inlet and a bypass pump outlet;
• a fuel filter having a filter inlet fluidly connected to the bypass pump outlet, and a filter outlet;
• a return manifold having a fuel inlet port fluidly connected to the fuel reservoir, a fuel outlet port fluidly connected to a fuel inlet of the fuel transfer pump, a flow channel placing the fuel inlet port in fluid communication with the fuel outlet port, a bypass outlet port proximate the fuel inlet port and fluidly connected to the bypass pump inlet, and a bypass inlet port proximate the fuel outlet port and fluidly connected to the fuel transfer pump;
• and
• an asymmetrical orifice disposed within the flow channel of the return manifold and separating the fuel inlet port and the bypass outlet port from the fuel outlet port and the bypass inlet port, the asymmetrical orifice comprising:
• a body having a first end surface and a second end surface,
• an inner surface defining a bore through the body extending from a first opening through the first end surface to a second opening through the second end surface, wherein the first opening has a first opening inner diameter and the second opening has a second opening inner diameter that is less than the first opening inner diameter, and
• a flow control contour in the second end surface surrounding the second opening of the bore,
• wherein the flow control contour is a recess formed into the body,
• wherein the body of the asymmetrical orifice engages the flow channel so that the fuel flows through the bore to place the fuel inlet port in fluid communication with the fuel outlet port.