* Clogged Fuel Filter (again): It's possible the new fuel filter was defective or became clogged very quickly. A very fine particle could have gotten lodged in a critical area. Check the fuel filter again.
* Low Fuel Pressure: Even with a new filter, there might not be enough fuel pressure reaching the engine. This could be due to:
* Faulty Fuel Pump: The fuel pump itself might be failing, despite initially seeming to work. The whirring sound you hear might be the pump struggling to build pressure.
* Clogged Fuel Line: A blockage somewhere in the fuel line between the tank and the engine could restrict fuel flow.
* Fuel Pump Relay: The relay that controls the fuel pump might be failing intermittently or completely.
* Faulty Fuel Pressure Regulator: This regulator controls the pressure in the fuel rail. A malfunction could prevent sufficient fuel from reaching the injectors.
* Other Engine Issues: While less likely if it ran fine after the filter change, the problem could be unrelated to the fuel system. Consider:
* Spark Plugs/Wires: A lack of spark would prevent the engine from starting.
* Crankshaft Position Sensor: This sensor tells the computer the engine's rotation. A faulty sensor will prevent starting.
* Cam Position Sensor: Similar to the crankshaft sensor but for the camshaft.
Troubleshooting Steps:
1. Check the fuel level: Make sure the tank isn't nearly empty. A low fuel level can sometimes cause problems.
2. Check the fuel filter (again): Inspect the filter for any obvious clogs or damage.
3. Check fuel pressure: This requires a fuel pressure gauge and is best done by a mechanic or someone familiar with automotive diagnostics. This will directly tell you if the pump is producing sufficient pressure.
4. Listen carefully to the fuel pump: Does it sound weak or different than before? A struggling pump will often make a different sound than a healthy one.
5. Check the fuel pump relay: Locate the fuel pump relay (consult your owner's manual) and try swapping it with a known good relay (if you have one).
6. Inspect fuel lines: Visually inspect the fuel lines for any kinks, cracks, or damage.
7. Have it professionally diagnosed: If you're not comfortable with the above steps, take your Explorer to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and efficiently.
Don't continue to crank the engine repeatedly if it doesn't start. This can drain the battery.
