1. Faulty fuel pump: The fuel pump is responsible for delivering fuel from the fuel tank to the fuel rail. A faulty fuel pump may not be able to generate enough pressure to deliver fuel to the fuel rail.
2. Clogged fuel filter: The fuel filter prevents debris from entering the fuel system. A clogged fuel filter can restrict fuel flow and prevent it from reaching the fuel rail.
3. Faulty fuel pressure regulator: The fuel pressure regulator controls the fuel pressure in the fuel rail. A faulty fuel pressure regulator may not be able to maintain the correct fuel pressure, which can prevent fuel from reaching the fuel rail.
4. Leaking fuel injector(s): The fuel injectors spray fuel into the engine's cylinders. Leaking fuel injector(s) can prevent fuel from reaching the fuel rail.
5. Clogged fuel line(s): The fuel lines carry fuel from the fuel tank to the fuel rail. Clogged fuel lines can restrict fuel flow and prevent it from reaching the fuel rail.
6. Faulty fuel pump control module (FPCM): The FPCM controls the operation of the fuel pump. A faulty FPCM may not be able to turn on the fuel pump, which can prevent fuel from reaching the fuel rail.
7. Faulty PCM: Powertrain control module (PCM) may not be providing the proper signals to the FPCM to enable the fuel pump to run correctly.
To diagnose the specific cause of the fuel delivery problem in your 2003 Ford Expedition, it is recommended to take it to a qualified mechanic or use appropriate diagnostic tools to narrow down the issue and address it accordingly.
