Methods and systems for operating an engine that includes two fuel pumps are described. In one example, a first fuel pump may be activated or remain activated in response to an engine shutdown request so that a second fuel pump may be cooled before the first fuel pump is deactivated in response to the engine shutdown request.

An engine control system for an engine includes: a pump control module configured to control a coolant pump; a block control module configured to control opening of a block valve; a fuel control module configured to control fueling of the engine; a coolant control module configured to control a position of a coolant valve; and an adjustment module configured to, when the coolant pump is pumping, the block valve is open, and the coolant valve is positioned such that an input is connected to an output, adjust the fueling of the engine such that fueling of the engine is fuel rich.

An engine control system for an engine includes: a pump control module configured to control a coolant pump; a block control module configured to control opening of a block valve; a fuel control module configured to control fueling of the engine; a coolant control module configured to control a position of a coolant valve; and an adjustment module configured to, when the coolant pump is pumping, the block valve is open, and the coolant valve is positioned such that an input is connected to an output, adjust the fueling of the engine such that fueling of the engine is fuel rich.

A lower limit setting portion of a fuel pump control system sets a lower limit value depending on an engine operating mode. For example, it sets a duty ratio of 0% as the lower limit value, when the engine operating mode is in a STOP mode in a turned-on condition of an ignition switch. A duty-ratio calculating portion carries out a feedback control in order that an actual fuel pressure comes closer to a target fuel pressure by use of the lower limit value and calculates a duty ratio for driving a fuel pump by the feedback control. An abnormal condition determining portion determines an abnormal condition based on the duty ratio and pump current. The abnormal condition determining portion further determines based on a remaining fuel amount whether the abnormal condition is caused by a disconnection or whether the abnormal condition is caused by an idling operation of the fuel pump due to fuel shortage.

A lower limit setting portion of a fuel pump control system sets a lower limit value depending on an engine operating mode. For example, it sets a duty ratio of 0% as the lower limit value, when the engine operating mode is in a STOP mode in a turned-on condition of an ignition switch. A duty-ratio calculating portion carries out a feedback control in order that an actual fuel pressure comes closer to a target fuel pressure by use of the lower limit value and calculates a duty ratio for driving a fuel pump by the feedback control. An abnormal condition determining portion determines an abnormal condition based on the duty ratio and pump current. The abnormal condition determining portion further determines based on a remaining fuel amount whether the abnormal condition is caused by a disconnection or whether the abnormal condition is caused by an idling operation of the fuel pump due to fuel shortage.

An engine includes a catalyst disposed inside an exhaust passage that guides exhaust discharged from a combustion chamber and a controller programmed to control a throttle valve and a fuel injector. If the engine is overheating, the controller is programmed to control the opening degree of the throttle valve or the injection amount of fuel from the fuel injector to decrease the rotational speed of the crankshaft and to control the injection amount of fuel from the fuel injector to set a target air-fuel ratio to a value richer than a stoichiometric air-fuel ratio.