1998 Infiniti QX4FACTORY OEM SERVICE PROCEDURE

Fuel Pump System Test: Frontier

  1. Turn ignition on. Listen for fuel pump operating sound. Fuel pump should operate for 5 seconds after ignition is turned on. If operating sound is not heard, go to next step. If operating sound is heard, system is functioning properly.
  2. Turn ignition off. Disconnect fuel pump relay. Fuel pump relay is located behind instrument panel, above parking brake lever. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 2 and No. 5 (Black/White wires). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fuse in main 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 along fuel tank edge. Check continuity between ground and fuel pump harness connector Black wire. Check continuity between fuel pump relay harness connector terminal No. 5 (White/Blue wire) and fuel pump harness connector White/Blue wire. Continuity should exist in both checks. 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 (White/Red 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 White/Red wire between PCM and relay.
  5. Check fuel pump relay. See RELAYS  under RELAYS & SOLENOIDS. Also check fuel pump. See 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.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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