Nissan Maxima Service and Repair Manual: Fuel pump

Description

*: ECM determines the start signal status by the signals of engine speed and battery voltage.

The ECM activates the fuel pump for several seconds after the ignition switch is turned ON to improve engine start ability. 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.

Component Function Check

1.CHECK FUEL PUMP FUNCTION

1. Turn ignition switch ON.
2. Pinch fuel feed hose with two fingers.

: Vehicle front (Illustration shows the view with intake air duct removed)

Fuel pressure pulsation should be felt on the fuel feed hose for 1 second after ignition switch is turned ON.

Diagnosis Procedure

1.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-I

1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Turn ignition switch ON.
4. Check the voltage between ECM harness connector and ground.

2.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-II

Check the voltage between IPDM E/R harness connector and ground.

3.DETECT MALFUNCTIONING PART

Check the following.

• IPDM E/R harness connector F10
• Harness for open or short between IPDM E/R and ECM

4.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-III

1. Disconnect "fuel level sensor unit and fuel pump" harness connector.
2. Check harness continuity between IPDM E/R harness connector and "fuel level sensor unit and fuel pump" harness connector

5.DETECT MALFUNCTIONING PART

Check the following.

• Harness connectors B10, E29
• Harness for open or short between "fuel level sensor unit and fuel pump" and IPDM E/R

6.CHECK FUEL PUMP GROUND CIRCUIT

1. Disconnect "fuel level sensor unit and fuel pump" harness connector.
2. Check the continuity between "fuel level sensor unit and fuel pump" harness connector and ground.

7.CHECK FUEL PUMP

8.CHECK INTERMITTENT INCIDENT

Component Inspection

1.CHECK FUEL PUMP

1. Turn ignition switch OFF.
2. Disconnect "fuel level sensor unit and fuel pump" harness connector.
3. Check resistance between "fuel level sensor unit and fuel pump" terminals as per the following.