1998 Nissan-Datsun Sentra BaseFACTORY OEM SERVICE PROCEDURE

Fuel Pump System Test: 240SX

  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 next to main fuse box panel on driver's side. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 and No. 3 (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 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 in trunk. Check continuity between ground and fuel pump harness connector Black wire. Check continuity between fuel pump relay harness connector terminal No. 5 (Black/Yellow wire) and fuel pump harness connector Black/Yellow wire. Continuity should exist in both circuits. If continuity exists in both circuits, go to next step. If continuity does not exist, repair open or short in appropriate wire.
  4. Disconnect PCM harness connector. Check continuity between PCM harness connector terminal No. 8 (Black/Pink wire) and fuel pump relay harness connector terminal No. 2. See Figure. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open or short in Black/Pink wire between PCM and fuel pump relay harness connectors.
  5. Check fuel pump relay. See RELAYS  under RELAYS & SOLENOIDS. If relay is okay, 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.