Fuel pump having improved pumping behavior

A fuel pump for delivering fuel, the fuel pump comprising:

• a piston (2) having a centerline (X), and
• a diaphragm seal element (3) that contacts an inner annular seal seat (4) and an outer annular seal seat (5) in a sealing manner when the piston is in a first position,
• wherein a centerline of the inner annular seal seat (4) and a centerline of the outer annular seal seat (5) coincide with the centerline of the piston (X),
• wherein components of the fuel pump satisfy an equation,
• wherein the equation is:
• (Ra2−ra2)/(ri+L)2=ra/ri,
• wherein ri is an inner radius of the inner annular seal seat (4) measured from the centerline of the piston (X),
• wherein ra is an inner radius of the outer annular seal seat (5) measured from the centerline of the piston (X),
• wherein Ra is a radius of the piston (2) measured from the centerline of the piston (X) to an outer circumference of the piston,
• wherein L is a difference between an outer radius (Ria) of the inner annular seal seat (4) measured from the centerline of the piston (X) and the inner radius (ri) of the inner annular seal seat (4), and
• wherein the piston (2) is configured to move from the first position and away from the diaphragm seal element (3) to create a region of low pressure to move the diaphragm seal element (3) away from the inner annular seal seat (4) and away from the outer annular seal seat (5).