Nissan Maxima 1993-1998 Repair Guide

Electric Fuel Pump

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REMOVAL & INSTALLATION



See Figures 1 through 8


CAUTION
Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well ventilated area. Do not allow fuel spray or vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.

  1. Refer to "Relieving Fuel System Pressure" procedure, in this section, and release the fuel pressure. Reducing the fuel pressure to zero is a very important step for correct removal of the electric fuel pump.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. To access the fuel pump, the rear seat bottom must be removed.
  6.  

If vehicle has no fuel pump access cover the fuel tank must be lowered or removed to gain access to the in-tank fuel pump.

  1. Unplug the fuel pump harness connector.
  2.  



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Fig. Fig. 1: Unplug the fuel pump assembly harness connector ...

  1. Remove the fuel pump access cover.
  2.  



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Fig. Fig. 2: ... then unscrew the fuel pump access cover ...



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Fig. Fig. 3: ... then push the grommet through the cover, followed by the connector

  1. Disconnect the fuel outlet and the return hoses. Use rags to catch any excess fuel.
  2.  



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Fig. Fig. 4: Keep in mind a small amount of fuel will escape when the lines are removed



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Fig. Fig. 5: It is a good idea to plug the lines after they are removed from the pump

  1. Remove the fuel pump assembly-to-fuel tank bolts, and carefully lift the fuel pump assembly from the fuel tank. Discard the O-ring. Place a clean rag over the fuel tank opening to prevent dirt from entering the fuel tank.
  2.  



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Fig. Fig. 6: After the lines are plugged, remove the screws that attach the fuel pump assembly to the fuel tank



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Fig. Fig. 7: Be careful not to damage the fuel level sender unit when removing the assembly

When removing or installing the fuel pump assembly, be careful not to damage or deform it. It is recommended that a new O-ring is installed when replacing the fuel pump assembly.



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Fig. Fig. 8: Be sure the O-ring doesn't fall into the fuel tank when removing the assembly

To install:
  1. Using a new O-ring, place the fuel pump assembly into the fuel tank.
  2.  
  3. Install the fuel pump assembly-to-fuel tank bolts and torque the bolts to 1.4-1.9 ft. lbs. (2.0-2.5 Nm).
  4.  
  5. Reconnect the fuel lines and the electrical connector.
  6.  
  7. Connect the negative battery cable, start engine and check for fuel leaks.
  8.  
  9. If all connections are secure, install the fuel pump access cover and the rear seat.
  10.  

Keep in mind that the engine may take longer to start, since the fuel pump has to prime itself and pressurize the system. Be sure the battery is in good condition.

On some models, the "Check Engine Light" will stay on after installation is completed. The memory code in the control unit must be erased. To erase the code, disconnect the battery cable for 10 seconds then reconnect it after installation of fuel pump.

TESTING



See Figure 9

  1. To inspect the electrical condition of the fuel pump, perform the following procedure:
    1. Turn the ignition switch OFF .
    2.  
    3. Unplug the fuel pump electrical connector.
    4.  
    5. Using an ohmmeter, set on the lowest scale, connect the probes to terminals a and c (for 1995-98 models, terminals 1 and 2 ). For VG30E engine models, the resistance should approximately 0 Ohms. For all other models, the resistance should be between 0.2 to 5.0 ohms; if not within specifications, the fuel pump may be faulty.
    6.  
    7. If the fuel pump resistance is OK, plug in the fuel pump electrical connector.
    8.  

  2.  
  3. Release the fuel pressure. Connect a fuel pressure gauge between the fuel filter outlet and fuel feed tube.
  4.  



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Fig. Fig. 9: Connecting a pressure gauge between the fuel filter outlet and the fuel rail inlet tube will allow an accurate reading of the fuel pressure

  1. Start the engine and read the pressure; it should be:

    1993-94 models: 36 psi (245 kPa)-At idle, fuel pressure regulator vacuum hose connected
     
    1995-98 models: 34 psi (235 kPa)-At idle, fuel pressure regulator vacuum hose connected
     
    All models: 43 psi (294 kPa)-Disconnected fuel pressure regulator vacuum hose, and the hose plugged
     

  2.  

Make sure the fuel filter is not blocked before replacing any fuel system components.

  1. Stop the engine. Disconnect the fuel pressure regulator vacuum hose from the intake manifold and plug the intake manifold opening.
  2.  
  3. Using a variable vacuum source, connect it to the fuel pressure regulator.
  4.  
  5. Start the engine and read the fuel pressure gauge as the vacuum is changed.
  6.  

The fuel pressure should decrease as the vacuum increases; if not, replace the fuel pressure regulator.

  1. If pressure is not as specified, replace the pressure regulator and repeat the test. If the pressure is still incorrect, check for clogged or deformed fuel lines, then replace the fuel pump.
  2.  

 
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