1993 Nissan-Datsun Sentra SE-R, StandardFACTORY OEM SERVICE PROCEDURE

Fuel Pump System Test (240SX)

  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 in fuse box next to battery. Turn ignition on. Measure voltage between ground and fuel pump relay harness connector terminals No. 1 (Black/White wire) and No. 5 (Black/White wire). For terminal identification, see Figure . Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check 10-amp fuse in main fuse box. Check harness continuity between fuse and fuel pump relay. Repair or replace as necessary.
  3. Turn ignition off. Disconnect fuel pump harness connector, located under rear seat. Check continuity between ground and fuel pump harness connector terminal "a" (Black wire). Check continuity between fuel pump relay harness connector terminal No. 3 (Black/Yellow wire) and fuel pump harness connector terminal "c" (Black/Yellow wire). For terminal identification, see Figure . Continuity should exist in both checks. If continuity exists in both checks, go to next step. If continuity does not exist, repair appropriate harness or connectors.
  4. Ensure ignition is off. Disconnect ECM harness connector. ECM is located behind passenger's kick panel. Check continuity between ECM harness connector terminal No. 104 (Black/Pink wire) and fuel pump relay harness connector No. 2 (Black/Pink wire). See Figure , Figure and Figure . Continuity should exist. If continuity exists, check fuel pump relay. See RELAYS  under RELAYS & SOLENOIDS. If relay is okay, check fuel pump. See FUEL PUMP TEST. If continuity does not exist, check harness between ECM and relay. Repair harness and 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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