2003 Mazda B2300 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Fuel Pump Inspection

  1. Check Fuel Pump For Operation -  Verify battery is fully charged. Verify fuel tank 4-pin harness connector is securely connected. With KOEO, connect scan tool to DLC. Select ACTIVE COMMAND MODE. Select OUTPUT TEST MODE. Press MODE to change to ALL ON mode. Press START to run fuel pump. Listen to fuel pump to verify fuel pump operation. Turn ignition off. If fuel pump operates, see FUEL DELIVERY SYSTEM  testing under SYSTEM TESTS. If fuel pump does not operate, go to next step.
  2. Check Fuel Pump For Continuity -  Disconnect fuel tank assembly 4-pin harness connector. Using a DVOM, check for continuity between fuel tank unit power circuit (Pink/Black wire) and ground (Black wire) circuit. If continuity is present, go to next step. If continuity is not present, replace faulty fuel pump.
  3. Check Voltage At Fuel Pump Vehicle Harness Connected -  Connect scan tool to DLC. With KOEO, select ACTIVE COMMAND MODE. Select OUTPUT TEST MODE. Press MODE to change to ALL ON mode. Press START to run fuel pump. Measure voltage at fuel tank assembly 4-pin harness connector (Pink/Black wire). If voltage reading is more than 10.5 volts, go to next step. If voltage reading is 10.5 volts or less, check fuel pump relay and Inertia Fuel Shutoff (IFS) switch. Repair as necessary.
  4. Check Fuel Pump Ground Circuit -  Disconnect fuel tank assembly 4-pin harness connector. Measure resistance between fuel pump ground circuit (Black wire) and chassis ground of fuel tank assembly 4-pin harness connector. If resistance reading is less than one ohm, ground circuit is okay. Recheck fuel pump. If resistance reading is one ohm or more, repair open circuit in Black wire between fuel tank assembly 4-pin harness connector and chassis ground.
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:

  • • 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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