Ignition System:
* Weak battery: This is the most common cause. A low charge or failing battery won't provide enough power to crank the engine. Test the voltage with a multimeter.
* Dirty or corroded battery terminals: Clean the terminals with a wire brush and baking soda solution.
* Faulty starter: The starter motor might be failing, causing it to struggle to turn the engine over. Listen for clicking sounds.
* Bad ignition switch: A worn or damaged ignition switch might not be providing a consistent connection.
* Ignition coil: This component supplies high voltage to the spark plugs. A failing coil will result in weak or no spark.
* Distributor cap and rotor: These components distribute the high voltage to the spark plugs. Cracks, corrosion, or worn components can disrupt the spark.
* Spark plugs and wires: Worn or fouled spark plugs and damaged wires prevent a strong spark.
Fuel System:
* Low fuel: Check the fuel gauge, but also consider a faulty fuel gauge.
* Clogged fuel filter: A dirty fuel filter restricts fuel flow to the engine.
* Fuel pump: A weak or failing fuel pump won't deliver enough fuel to the engine. You might hear a humming sound from the pump when the key is turned.
* Clogged fuel injectors: Restricted fuel injectors prevent proper fuel delivery.
Other Possibilities:
* Alternator: If the alternator is failing, the battery won't charge properly.
* Sensor issues: Various sensors, such as the crankshaft position sensor or temperature sensor, can prevent the engine from starting. These require diagnostic tools to check.
* Timing issues: An improperly timed engine won't start. This is more advanced and requires expertise.
* Security system (if equipped): An aftermarket security system could be preventing the vehicle from starting.
To diagnose the problem, you'll need to systematically check these areas. Starting with the simplest things like the battery and terminals is a good approach. If you're not comfortable working on cars, taking it to a mechanic is the safest option.
