How to Check for Fuel Delivery in a Nissan Maxima
- 1). Relieve the pressure in the Nissan Maxima model's fuel system. Disengage the fuel pump fuse. Start the engine and let it run until it stalls. Turn the ignition to the off position and disconnect the negative battery cable.
- 2). Disconnect the fuel pressure sensor vacuum hose. Check for fuel in the line. If there is fuel present in the line, the fuel delivery problem is likely due to a faulty fuel pump pressure regulator. If there is no fuel in the line, reattach the vacuum hose and continue with the fuel delivery diagnostic.
- 3). Twist off the fuel pressure test port cap and attach a pressure gauge to the fuel pressure valve located between the pressure regulator and fuel filter using a "T" connector. Open the manual valve on the gauge and let the fuel drain through the connected tube into an approved container.
- 4). Reconnect the negative battery cable and start the engine. Check the pressure gauge. It needs to register approximately 36 psi. Remove the vacuum hose and check the gauge again. It needs to register approximately 43 psi. Pressure that's too high indicates a malfunctioning pressure regulator. Low pressure indicates a clogged fuel filter or a broken fuel pump that needs to be replaced.
- 5). Cut the engine, relieve system pressure again and remove the negative battery cable.
- 6). Remove the filter and the fuel pump combination assembly. Disconnect the electrical connector to the pump located under the back seat. Disengage the fuel lines that run to the pump. Disengage the locking ring and assembly for the fuel gauge. Disconnect the fuel gauge from its tube and connector. Lift the pump out of the fuel tank by pressing the two locking tabs together to release the holding bracket.
- 7). Examine the filter for clogs and replace it with a new one if necessary. If there are no clogs, the fuel delivery problem is probably caused by a faulty fuel pump.
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