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Home >> Nissan-Datsun >> 1998 >> Sentra Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Tests >> Fuel System >> Fuel Pump System Test >> Pathfinder & QX4
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Pathfinder & QX4

  1. 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.
  2. Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located in relay box, on right front inner fender panel. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 2 (Black/Yellow wire) and No. 3 (Black/Yellow wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse in fuse box. Check for open or short in appropriate wire between fuse and fuel pump relay. Repair or replace as necessary.
  3. Turn ignition off. Disconnect fuel pump harness connector (located under vehicle). 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 (White/Blue 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.
  4. 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. 1 (Red/Blue 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 Red/Blue wire between PCM and relay.
  5. Check fuel pump relay. See RELAYS  under RELAYS & SOLENOIDS. Also check fuel pump. See FUEL PUMP . If necessary, replace fuel pump relay or fuel pump. If fuel pump relay and fuel pump are okay, disconnect and inspect harness and connectors for pushed-out, bent, damaged or corroded terminals. Repair harness or connectors as necessary.
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