1. Check the Obvious:
* Fuel: Is the gas tank nearly empty? A low fuel level can sometimes cause starting problems.
* Battery Cables: Inspect the battery terminals for corrosion. Clean them with a wire brush and baking soda if necessary. Loose connections can prevent sufficient power from reaching the starter, even though it cranks.
* Fuel Pump: Listen carefully near the fuel tank while someone tries to crank the engine. You should hear a whirring sound from the fuel pump for a second or two when the key is turned to the "on" position (before cranking). If you don't hear it, the fuel pump relay or the pump itself might be faulty.
2. Ignition System Checks:
* Spark Plugs and Wires: Have the spark plugs and wires inspected or replaced. Worn or fouled plugs are a common cause of no-start conditions. Cracked or damaged wires can prevent a spark from reaching the plugs.
* Distributor (if applicable): While less common in newer vehicles, some 2005 Explorers might still have a distributor. Check the cap and rotor for wear or cracks.
* Camshaft Position Sensor (CMP) and Crankshaft Position Sensor (CKP): These sensors tell the computer the engine's position, crucial for timing the spark. A faulty sensor will prevent starting. These require diagnostic tools to properly test.
* Ignition Coil: This component delivers high voltage to the spark plugs. A failing coil can cause misfires or a complete lack of spark.
3. Fuel System Checks (beyond the pump):
* Fuel Filter: A clogged fuel filter restricts fuel flow to the engine. This should be replaced periodically as part of routine maintenance.
* Fuel Pressure: This requires a fuel pressure gauge to accurately measure the pressure in the fuel rail. Low pressure indicates a problem with the fuel pump, fuel filter, or fuel pressure regulator.
* Fuel Injectors: Faulty injectors can prevent fuel from being sprayed into the cylinders. Testing injectors usually requires specialized tools.
4. Computer System Checks:
* OBD-II Scanner: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the vehicle's computer. These codes can pinpoint the problem area. Auto parts stores often offer free code reading services.
* PCM (Powertrain Control Module): In rare cases, a problem with the PCM itself can prevent starting. This requires professional diagnosis and often replacement.
Important Considerations:
* Professional Diagnosis: If you're not comfortable performing these checks yourself, take your Explorer to a qualified mechanic. Improper diagnosis can lead to unnecessary parts replacement.
* Safety: Always disconnect the negative battery terminal before working on any electrical components.
In summary: The cranking but not starting issue in your 2005 Ford Explorer is likely due to a problem with either the ignition system (spark plugs, wires, coil, sensors) or the fuel delivery system (pump, filter, injectors). Use the troubleshooting steps above, starting with the simplest checks, and consider professional help if you can't identify the cause. The OBD-II codes will be particularly helpful in narrowing down the possibilities.
