Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1998 Infiniti QX4FACTORY OEM SERVICE PROCEDURE
Fuel Pump System Test: Maxima
- Turn ignition on. With fingers, pinch fuel feed hose at fuel filter. Fuel pressure pulsation should be felt for 5 seconds after ignition is turned on. If pulsation is not felt, go to next step. If pulsation is felt, system is functioning properly.
- Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located under left kick panel. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (Brown wire) and No. 3 (Black/White wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuses in fuse box. See WIRING DIAGRAMS article. Check for open or short in appropriate wire between fuses and fuel pump relay. Repair or replace as necessary.
- Turn ignition off. Disconnect fuel pump harness connector (located under rear seat). Check continuity between ground and fuel pump harness connector terminal No. 2 (Black wire). Also check continuity between fuel pump harness connector terminal No. 1 (Black/Yellow wire) and fuel pump relay harness connector terminal No. 5. Continuity should exist in both circuits. If continuity exists in both circuits, go to next step. If continuity does not exist in either circuit, repair open or short in appropriate wire.
- Ensure ignition is off. Disconnect PCM harness connector. PCM is located under center of instrument panel (connector is on driver's side). Check continuity between fuel pump relay harness connector terminal No. 2 (Black/Pink wire) and PCM harness connector terminal No. 11. See Figure. If continuity exists, go to next step. If continuity does not exist, repair open or short in Black/Pink wire between PCM and relay.
- Check fuel pump relay. See RELAYSΒ under RELAYS & SOLENOIDS. Also check fuel pump. See FUEL PUMPΒ . If necessary, replace fuel pump relay or fuel pump. If fuel pump relay and fuel pump are okay, check circuit harness connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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