Nissan Fuel Pump System
- Properly relieve the fuel system pressure.
- Remove the rear seat.
- Remove the fuel pump cover.
- Label and disconnect the electrical harness.
- Label and disconnect the fuel hoses.
Fig. Fig. 5: The fuel pump assembly consists of the pump cover (1), cover gasket (2), electric fuel pump (1), and strainer (2)
One hose is a high pressure fuel input hose and the other is a low pressure return hose. Different hose clamps are used on each of the hoses.
- Matchmark the locking ring with the body for installation reference. This is to prevent overtightening of the locking ring.
- Remove the locking ring using a special lock ring tool.
It may be possible to use a large set of locking jaw pliers to loosen the lock ring. However, extreme caution must be used to not damage the plastic ring or strip the plastic threads.
- Remove the fuel pump and sending unit from the fuel tank.
- Inspect the sealing gasket and replace if damaged.
- Install the fuel pump and sending unit in the fuel tank.
- Install the locking ring by hand and tighten using a special lock ring tool.
It may be possible to use a large set of locking jaw pliers to tighten the lock ring. However, extreme caution must be used to not damage the plastic ring or strip the plastic threads. Tighten the locking ring until the matchmarks align.
- Connect the fuel hoses using the proper hose clamps for the high pressure and low pressure hoses.
- Connect the electrical harness.
- Install the fuel pump cover.
- Install the rear seat.
Please Note: It is important to note that the fuel filter should be replaced once a year. Luckily, it is very inexpensive and the process is quite simple. For the Nissan Altima, the fuel filter is part of the car’s fuel pump assembly.
TESTING
Electrical Test
Remove the fuel pump inspection cover to access the fuel pump electrical harness.
Turn the ignition switch OFF .
Disconnect the fuel pump electrical connector.
Measure the resistance between the fuel pump terminals. Resistance should be 0.2-3.0 ohms @ 55°F (23°C).
If resistance is not within specification, the fuel pump may be faulty.
If the fuel pump resistance is within specification, check fuel pressure.
Pressure Test
See Figures 6 and 7
Fig. Fig. 6: Connect a fuel pressure gauge inline between the fuel filter and fuel feed line
Fig. Fig. 7: Fuel pressure can be checked using an inexpensive pressure/vacuum gauge
Properly relieve the fuel system pressure.
Connect a fuel pressure gauge between the fuel filter outlet and fuel feed hose.
Start the engine and read the fuel pressure.
Fuel pressure should be approximately 21 psi (272 kPa) a few seconds after the ignition switch is turned from OFF to ON .
Fuel pressure should be approximately 12 psi (213 kPa) with the engine idling.
Stop the engine and disconnect the fuel pressure regulator vacuum hose.
Plug the vacuum hose at the intake manifold and connect a hand operated vacuum pump to the pressure regulator.
Start the engine and note the fuel pressure as vacuum is applied and released.
Fuel pressure should decrease as vacuum increases.
If fuel pressure does not respond as specified, the fuel pressure regulator may be faulty.
If fuel pressure responds as specified, but fuel pressure is not within specification, the fuel pump may be faulty.
REMOVAL & INSTALLATION
See Figures 1, 2 and 3
Fig. Fig. 1: On the Altima, the fuel pressure regulator is attached to the passenger's side end of the fuel rail by two bolts
Fig. Fig. 2: Fuel pressure is controlled by a vacuum line connected to the fuel pressure regulator
Fig. Fig. 3: Always use a new O-ring when installing the fuel pressure regulator
Properly relieve the fuel system pressure.
Disconnect and cap the fuel return line at the regulator.
Disconnect the vacuum line from the regulator.
Remove the bolts securing the pressure regulator to the fuel rail.
Place a rag under the fuel rail to absorb any remaining fuel.
Remove the regulator from the fuel rail and discard the O-ring.
To install:
Install a new O-ring on the regulator and position it on the fuel rail.
Tighten the regulator securing bolts to 26-34 inch lbs. (3-4 Nm).
Connect the vacuum line to the regulator.
Connect the fuel return line to the regulator.
Pressurize the fuel system and check for leaks.
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