Troubleshooting Ford F150

Fuel pump

1. The fuel pump is located inside the fuel tank. Sit inside the vehicle with the windows closed, turn the ignition key to On (not Start) and listen for the sound of the fuel pump as it’s briefly activated. You will only hear the sound for a second or two, but that sound tells you that the pump is working. Alternatively, have an assistant listen at the fuel filler cap.

Ford F150 Fuel and exhaust systems_Troubleshooting _Fuel system related underhood fuse/ relay box details

Fuel system related underhood fuse/ relay box details

1 Fuel pump relay 51 (supplies power to the Fuel Pump Control Module)
2 Fuel pump relay fuse F56 (20 amp; always hot)
3 Fuel pump fuse F9 (30 amp; not all models)

2. If the pump does not come on, check the fuel pump fuse(s) and fuel pump relay If the fuse(s) and relay are okay, check the wiring back to the Fuel Pump Driver Module (FPDM — see Fuel Pump Driver Module (FPDM) – replacement) and fuel pump. If the fuses, relay and wiring are okay, the fuel pump is probably defective. If the pump runs continuously with the ignition key in the On position, the Powertrain Control Module (PCM) is probably defective. Have the PCM checked by a professional mechanic.

Fuel injection system

Caution: The following procedure applies to the complete SFI system and the fuel system before the high-pressure pump on Dl systems. Dl systems operate under very high pressures and require special tools to diagnose correctly.

Note: The following procedure is based on the assumption that the fuel pump is working and the fuel pressure is adequate (see Fuel pump/fuel pressure – check).

3. Check all electrical connectors that are related to the system. Check the ground wire connections for tightness.

4. Verify that the battery is fully charged (see Engine electrical systems).

5. Inspect the air filter element (see Tune-up and routine maintenance).

6. Check all fuses related to the fuel system (see Chassis electrical system).

7. Check the air induction system between the throttle body and the intake manifold for air leaks. Also inspect the condition of all vacuum hoses connected to the intake manifold and to the throttle body.

8. Remove the air intake duct from the throttle body and look for dirt, carbon, varnish, or other residue in the throttle body, particularly around the throttle plate. If it’s dirty, clean it with carb cleaner, a toothbrush and a clean shop towel.

Ford F150 Fuel and exhaust systems_Troubleshooting _An automotive stethoscope is used to listen to the fuel injectors in operation

An automotive stethoscope is used to listen to the fuel injectors in operation

9. With the engine running, place an automotive stethoscope against each injector, one at a time, and listen for a clicking sound that indicates operation

Warning: Stay clear of the drivebelt and any rotating or hot components.

Note: This check can only be performed on the V8 engine (on the V6 engines the injectors are concealed).

10. If you can hear the injectors operating, but the engine is misfiring, the electrical circuits are functioning correctly, but the injectors might be dirty or clogged. Try a commercial injector cleaning product (available at auto parts stores). If cleaning the injectors doesn’t help, replace the injector(s).

11. If an injector is not operating (it makes no sound), disconnect the injector electrical connector and measure the resistance across the injector terminals with an ohmmeter. Compare this measurement to the other injectors. If the resistance of the non-operational injector is quite different from the other injectors, replace it.

12. If the injector is not operating, but the resistance reading is within the range of resistance of the other injectors, the PCM or the circuit between the PCM and the injector might be faulty.

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