If you suspect insufficient fuel delivery, first check the battery to ensure it is fully charged, inspect the fuel filter for obstructions, and examine the fuel line and quick-connect fittings for leaks. Verify that the fuel pump operates by removing the fuel filler cap and having someone turn the ignition switch to ON while you listen for a brief whirring noise. If there is no sound, check the fuel pump relay fuse, the fuel pump relay, and the Inertia Fuel Shutoff (IFS) switch. For 2011 and later 3.5L V6 models, if a code is set for the pressure sensor, access it by removing the intake manifold. If the pump does not turn on, check the fuel pump relay fuse and relay, which are located in the passenger compartment fuse and relay box for 2008 and earlier models, or in the Battery Junction Box for 2009 and later models. If the fuse and relay are functional but the pump still does not operate, inspect the fuel pump circuit. To reset the IFS switch, ensure the ignition is OFF, then push the large button on top of the switch. If the pump still does not run, check the wiring harness for loose connectors or damage. If the fuel pump runs but a problem persists, proceed to check the fuel pump pressure. Obtain a fuel pressure gauge capable of measuring above the specified operating range and fittings suitable for teeing into the fuel system. Relieve the fuel system pressure, disconnect the quick-connect fitting between the fuel delivery hose and the fuel rail, and tee in the fuel pressure gauge. Start the engine and let it idle; the fuel pressure should be within the operating range. If the pressure is higher than specified, the pump, Fuel Pump Driver Module (FPDM), or Powertrain Control Module (PCM) may be defective. If the pressure is lower than specified, inspect the fuel delivery lines and hoses for obstructions or kinks, check for leaks at quick-connect fittings, replace the fuel filter, and re-check the pressure. If everything appears fine, remove the fuel pump/fuel level sensor assembly to inspect the fuel pump inlet strainer. If the hold pressure is less than specified after waiting five minutes, it may indicate a leak in the fuel delivery line or quick-connect fitting, leaking fuel injectors, or a defective fuel pump. After testing, relieve the fuel pressure, remove the gauge, and reconnect the fuel delivery line to the fuel rail.
Posted by FordPartsGiant Specialist 
