* Fuel System:
* Empty or low fuel: Sounds obvious, but check the fuel gauge and if you're unsure, try adding some fuel.
* Fuel pump failure: The pump might be dead, weak, or not getting power. You might hear a buzzing sound from the fuel pump when you turn the key to the "on" position (but not cranking). Lack of buzzing suggests a problem with the pump or its power supply.
* Clogged fuel filter: A blocked filter restricts fuel flow to the engine.
* Fuel injectors: They might be clogged, faulty, or not receiving the correct signal to open.
* Fuel pressure regulator: This could be faulty, leading to incorrect fuel pressure.
* Ignition System:
* Spark plugs: They could be fouled, worn out, or have poor connections. Check their condition and gap.
* Ignition coil: This supplies the high voltage to the spark plugs. A faulty coil will prevent sparking.
* Ignition control module (ICM): This controls the ignition timing and spark. A faulty ICM is a common problem in older Mustangs.
* Distributor cap and rotor: These components can wear out, causing poor spark distribution. Check for cracks, corrosion, or wear.
* Cranking sensor (or crankshaft position sensor): This sensor tells the computer the engine's rotational position for proper ignition timing. A faulty sensor prevents the computer from commanding a spark.
* Ignition wiring: Look for any damaged, loose, or corroded wires in the ignition system.
* Computer/Sensors:
* Computer (PCM/EEC-IV): While less common, a faulty computer can prevent the engine from starting. This is usually diagnosed via diagnostic codes (see below).
* Mass airflow sensor (MAF): A faulty MAF sensor can provide incorrect information to the computer, leading to a no-start condition.
* Throttle position sensor (TPS): Similar to the MAF, a faulty TPS can cause starting problems.
* Other Possibilities:
* Security system: If your Mustang has an aftermarket or factory alarm/immobilizer, it could be preventing the engine from starting.
* Poor Battery Connection: Make sure your battery terminals are clean, tight, and corrosion-free. A weak battery can also cause a no-start condition even if it cranks the engine.
Troubleshooting Steps:
1. Check for diagnostic trouble codes (DTCs): Your Mustang likely has a diagnostic system. There are several ways to retrieve these codes (consult your owner's manual or online resources for your specific year and model). These codes can point directly to the problem.
2. Check fuel pressure: You'll need a fuel pressure gauge to do this. This directly tests the fuel system's ability to deliver fuel.
3. Check for spark: Remove a spark plug, ground it to the engine block, and crank the engine. You should see a spark. If not, investigate the ignition system components.
4. Inspect the obvious: Check all fuses and relays related to the fuel system and ignition. Look for any obvious signs of damage or corrosion in the wiring harness.
Without more information, it's impossible to pinpoint the exact cause. Start with the simpler checks (fuel, battery, obvious visual inspections), then move to more complex diagnostics if necessary. If you're not comfortable working on cars, it's best to take it to a mechanic.
