Pumping unit for feeding fuel, preferably diesel fuel, to an internal combustion engine

A pumping unit for feeding fuel to an internal combustion engine, the pumping unit comprising a high-pressure pump (2) for feeding the fuel to the internal combustion engine;

• a pre-feed pump (3) for feeding the fuel from a storage tank to the high-pressure pump (2);
• an intake duct (49) for drawing the fuel into the pre-feed pump (3);
• and a delivery duct (50) for feeding the fuel from the pre-feed pump (3) to the high-pressure pump (2);
• the pre-feed pump (3) comprising an electric motor (37) comprising, in turn, a stator (38), a rotor rotatably engaged inside the stator (38), and a first gearing (40) formed on the rotor;
• a second gearing (42) engaged with the first gearing (40);
• and a pump body (32) configured to define a first containing chamber (47) for housing internally the first and second gearings (40, 42) and a second containing chamber (48) for housing internally the stator (38);
• wherein the first containing chamber (47) is fluidly connected to the intake duct (49) and is configured to deliver fuel to the delivery duct (50), wherein the pre-feed pump (3) further comprises a connection duct (51) formed through the pump body (32) so as to connect together the second containing chamber (48) and the intake duct (49) such that, during operation of the pre-feed pump, fuel that has seeped between the pump body (32) and the first and second gearings (40, 42) and moved from the first containing chamber (47) to the second containing chamber (48) is returned to the intake duct (49) upstream of the first containing chamber (47).