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Fuel Delivery System

    NOTE: DTC P0148, uses this testing procedure to diagnose detection of at least one bank lean at wide open throttle. No other testing is required.
  1. Check System Integrity -  Visually inspect complete fuel delivery system, including fuel lines, connections, relays, damage to fuel tank, fuel pump, fuel pressure regulator, fuel pulse damper and fuel injector areas for leaks, looseness, cracks, kinks, pinching, or abrasion caused by a collision or mishandling. Visually inspect electrical harnesses and connectors for loose pins, corrosion, abrasion, or other damage from collision or mishandling. Verify vehicle has followed maintenance schedule. Verify Inertia Fuel Shutoff (IFS) switch is set. Refer to INERTIA FUEL SHUTOFF SWITCH under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - B2300, B3000, B4000 & TRIBUTE article. Verify battery is fully charged (12.5 volts or more). Verify electrical/fuse integrity. Verify fuel level is sufficient. If any concern has been found, repair as necessary. After repair, rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  2. Check For Voltage At Fuel Pump Harness Connector -  Disconnect fuel pump 4-pin harness connector at fuel pump. Turn ignition on, engine off. Connect scan tool. Select DIAGNOSTIC DATA LINK. Select PCM. Select ACTIVE COMMAND MODES. Select OUTPUT TEST MODE. Select FUEL PUMP PID. Press MODE to change to ALL ON MODE. Press START to turn on fuel pump circuit. Connect a DVOM between fuel pump power circuit (Pink/Black wire) and fuel pump ground circuit (Black wire) at fuel pump 4-pin harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. If voltage reading is more than 12.5 volts, restore vehicle to original condition and go to next step. If voltage reading is 12.5 volts or less, check for open or short in fuel pump power and ground circuits. After repair, restore vehicle to original condition.
  3. Check Fuel Filter For Proper Maintenance -  Locate and inspect the vehicle maintenance schedule and fuel filter. If fuel filter was serviced according to schedule, go to next step. If fuel filter was not changed according to schedule, replace fuel filter. After repair, go to next step.
    4. NOTE: Fuel pump will only operate for about 8 seconds when OUTPUT TEST MODE is selected and activated.
  4. Check Fuel Pressure -  Install fuel pressure tester. Release fuel pressure. See FUEL PRESSURE RELEASE under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. Turn ignition on, engine off. Connect scan tool to DLC. Select DIAGNOSTIC DATA LINK. Select PCM, ACTIVE COMMAND MODES, OUTPUT TEST MODE and FUEL PUMP PID. Press MODE to change to ALL ON MODE. Press START to run fuel pump. If fuel pressure is 55-70 psi (380-482 kPa), go to next step. If fuel pressure is more than 70 psi (482 kPa), replace fuel pump module. See FUEL PUMP under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. After repair, return vehicle to original condition and recheck fuel pressure. If fuel pressure is less than 55 psi (380 kPa), go to step  6.
  5. Check Fuel Injector Flow And Leakage -  Check injectors for leakage and flow rate using an injector tester. Flow rate specification:
    • 17 lb/hr (7.84 kg/hr) for 2.0L
    • 22 lb/hr (10.1 kg/hr) for 3.0L
    If flow rate and leakage rate for injectors tested are within specification, ensure no other leaks are present and replace fuel pump module. See FUEL PUMP under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. If flow rate and leakage rate are not as specified, replace faulty fuel injector(s). After repair, restore vehicle to original condition and recheck fuel pressure.
  6. Check Pulse Damper Diaphragm -  Start engine and run for 10 seconds. Turn ignition off. Wait 10 seconds and then start engine and run for 10 seconds. Turn ignition off. Remove vacuum hose from fuel pressure regulator or pulse damper port. Inspect for fuel in vacuum hose at fuel pressure regulator or pulse damper end. If vacuum hose and fuel pressure regulator or pulse damper port are free of fuel, go to next step. If vacuum hose, fuel pressure regulator or pulse damper port have fuel present, replace faulty fuel pressure regulator or pulsation damper.
  7. Check Fuel Supply Line For Restriction -  Release fuel pressure. See FUEL PRESSURE RELEASE under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. Disconnect fuel supply line at fuel rail and fuel pump. Check fuel supply line for restrictions due to blockage, kinking, or pinching. Apply 3-5 psi (21-34 kPa) regulated shop air pressure to fuel supply line. If air flows freely through fuel supply line, replace fuel pump. If air does not flow freely through fuel supply line, repair restriction as necessary. After repair, restore vehicle to original condition and recheck fuel pressure.
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