System Description

WARNING: This page is about a different car, the 2008 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.

FUEL PUMP

Sensor

Input Signal to ECM

ECM Function

Actuator

Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)

Engine speed⁽¹⁾

Fuel pump control

Fuel pump relay

Battery

Battery voltage⁽¹⁾

⁽¹⁾	ECM determines the start signal status by the signals of engine speed and battery voltage.

The ECM activates the fuel pump for 1 second after the ignition switch is turned ON to improve engine startability. If the ECM receives a engine speed signal from the camshaft position sensor (PHASE), it knows that the engine is rotating, and causes the pump to operate. If the engine speed signal is not received when the ignition switch is ON, the engine stalls. The ECM stops pump operation and prevents battery discharging, thereby improving safety. The ECM does not directly drive the fuel pump. It controls the ON/OFF fuel pump relay, which in turn controls the fuel pump.

FUEL PUMP OPERATION

Condition	Fuel pump operation
Ignition switch is turned to ON.	Operates for 1 second.
Engine running and cranking	Operates.
When engine is stopped	Stops in 1.5 seconds.
Except as shown above	Stops.