Silenced fuel pump for a direct injection system

A fuel pump (4) for a direct-injection system provided with a common rail (3), said fuel pump (4) comprising:

• a pumping chamber (14) defined in a main body (12);
• a piston (15) that is mounted in a sliding manner inside said pumping chamber (14) to cyclically vary volume of said pumping chamber (14);
• a suction channel (17) connected to said pumping chamber (14) and regulated by a suction valve (18);
• a delivery channel (19) connected to said pumping chamber (14) and regulated by a delivery valve (20);
• and
• a flow-rate-adjustment device (6) that is mechanically coupled to said suction valve (18) to keep, when necessary, said suction valve (18) substantially open during pumping of said piston (15) and includes a control rod (21) that is coupled to said suction valve (18) and an electromagnetic actuator (22) that acts on said control rod (21) and has a one-way hydraulic brake (28) that is integral to and substantially slows movement of said control rod (21).