Fuel System Issues:
* Empty or Low Fuel: The most obvious, but often overlooked. Check your fuel gauge.
* Fuel Pump Failure: The pump might be malfunctioning, not delivering enough fuel, or completely dead. You might hear a faint whirring sound from the fuel pump during cranking if it's struggling.
* Fuel Filter Clog: A clogged fuel filter restricts fuel flow to the engine.
* Clogged Fuel Injector(s): Injectors might be clogged, preventing proper fuel delivery to the cylinders.
* Bad Fuel Pressure Regulator: This regulates fuel pressure; a faulty one can lead to incorrect fuel delivery.
Ignition System Issues:
* Spark Plug Problems: Worn, fouled, or damaged spark plugs prevent ignition.
* Spark Plug Wires (Ignition Coil Packs): Damaged or loose wires can interrupt the spark. Cracked or broken coil packs are a common failure point, especially on older Explorers.
* Ignition Coil Failure: The coil doesn't generate enough high voltage to fire the spark plugs.
* Distributor Issues (older models only): Older Explorers with distributors might have problems with the distributor cap, rotor, or the distributor itself.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position; a faulty one prevents proper ignition timing.
* Cam Position Sensor (CMP Sensor): Similar to the CKP sensor, but for the camshaft. A fault here will prevent the engine from starting.
Other Potential Causes:
* Low Battery Voltage: Even if the engine turns over slowly, it might not have enough power to consistently ignite the fuel.
* Security System Issues: The vehicle's anti-theft system might be preventing the engine from starting. Try rechecking the key fob, or check for any error messages.
* Bad PCM (Powertrain Control Module): The computer controlling the engine might be faulty. This is less common but possible.
* Immobiliser problems: Check the immobiliser system if your key is recognised but the car still won't start.
* Air Intake System Problems: A severely restricted air intake (e.g., blocked air filter) can prevent the engine from starting.
Troubleshooting Steps:
1. Check the obvious: Fuel level, battery voltage (have it tested!), and listen for unusual noises.
2. Check for error codes: Use an OBD-II scanner to read diagnostic trouble codes (DTCs). This can pinpoint the problem area.
3. Inspect spark plugs and wires: Check for damage, wear, or loose connections.
4. Listen carefully during cranking: Pay attention to any unusual sounds that might indicate a failing component (fuel pump whirring, unusual clicking noises).
Important Note: Without proper diagnostic tools and some mechanical knowledge, accurately diagnosing this issue can be challenging. If you're not comfortable working on your vehicle, it's best to take it to a qualified mechanic for diagnosis and repair. Attempting repairs without proper knowledge could lead to further damage.
