Fuel pump control system

A fuel pump control system for an internal combustion engine mounted in an automotive vehicle comprising:

• a relay device for supplying electric power from a vehicle battery to a fuel pump when the relay device is turned on, so that the fuel pump supplies fuel from a fuel tank to the internal combustion engine;
• a switching device provided in a power supply path for supplying the electric power to the fuel pump and connected in series with the fuel pump, the switching device being turned on or turned off depending on a pump driving signal;
• and
• an electronic control unit for calculating a first duty ratio for the pump driving signal based on a target fuel pressure, an actual fuel pressure and an engine operating mode, to carry out a feedback control with the first duty ratio so that the actual fuel pressure comes closer to the target fuel pressure,
• the electronic control unit determining whether there is an abnormal condition in an operation of the fuel pump, based on the first duty ratio for the feedback control and pump current flowing through the fuel pump,
• the electronic control unit further determining whether the abnormal condition is caused by a disconnection in the power supply path for the fuel pump or whether the abnormal condition is caused by an idling operation of the fuel pump due to shortage of the fuel, based on information relating to a remaining fuel amount in the fuel tank,
• the electronic control unit calculating a first predetermined value and sets the first predetermined value as a second duty ratio, when it determines that the abnormal condition is caused by the idling operation of the fuel pump due to the shortage of the fuel, so that the operation of the fuel pump is stopped with the pump driving signal having the second duty ratio of the first predetermined value, and
• the electronic control unit calculating a second predetermined value and sets the second predetermined value as the second duty ratio, when it determines that the abnormal condition is caused by the disconnection in the power supply path, so that the pump driving signal having the second duty ratio of the second predetermined value is continuously applied to the switching device, wherein the second predetermined value is larger than the first predetermined value.