Fuel from the tank is pumped into the fuel feed line (OUT) and then to the injectors, by means of a pump located on a flange installed at the bottom of the fuel tank. The flange also incorporates the pressure regulator that controls the fuel feed pressure and keeps it constant at a higher value than the negative pressure generated by the engine. Fuel that is not injected in the intake hoses returns to the flange and then to the tank by way of a return hose (IN).