System Description

Fig 1: Fuel Pressure Control - System Diagram

Courtesy of NISSAN MOTOR CO., U.S.A.

Low fuel pressure control

• The low fuel pressure pump is controlled by the fuel pump control module (FPCM) and pumps fuel according to a driving condition. The pumped fuel passes through the fuel filter and is sent to the high pressure fuel pump. FPCM controls the low pressure fuel pump, according to a signal from ECM as shown in the table below.
  FUEL FLOW CONDITION
  
  

  Conditions	Amount of fuel flow	Supplied voltage
  After a laps of 1 second after ignition ON	OFF	0 V
  For 1 second after turning ignition switch ON Engine is running under low load and low speed conditions	Low	Approximately 8.5 V
  Engine cranking Engine coolant temperature is below 10°C (50°F) Engine is running under high load and high speed conditions	High	Battery voltage (11 - 14 V)
  Except the above	Mid	Approximately 10 V

• Low fuel pressure is adjusted by the fuel pressure regulator.

High fuel pressure control

• The high pressure fuel pump raises the pressure of the fuel sent from the low pressure fuel pump. Actuated by the camshaft, the high pressure fuel pump activates the high pressure fuel pump solenoid based on a signal received from ECM, and adjusts the amount of discharge by changing the timing of closing the inlet check valve to control fuel rail pressure.