Fuel System:
* Fuel Pump: A weakening fuel pump might struggle to supply enough fuel at high demand (full throttle at high speeds). This is a common cause of hesitation under load.
* Fuel Filter: A clogged fuel filter restricts fuel flow, leading to similar symptoms.
* Fuel Injectors: Clogged or failing fuel injectors can't deliver the necessary fuel, causing hesitation. This is more likely if the hesitation is consistent across the RPM range at high speeds.
* Fuel Pressure Regulator: A malfunctioning regulator could deliver incorrect fuel pressure, leading to a lean condition and hesitation.
Ignition System:
* Worn Spark Plugs/Wires: Old, worn, or improperly gapped spark plugs can misfire under high load, causing hesitation. Worn spark plug wires can also lead to poor ignition.
* Ignition Coil(s): A failing ignition coil may not provide sufficient spark to ignite the fuel-air mixture consistently, especially under stress.
* Distributor Cap and Rotor (if applicable): For older 302s with distributors, worn or cracked components can cause intermittent spark delivery.
Air Intake System:
* Mass Airflow Sensor (MAF): A faulty MAF sensor provides incorrect air/fuel mixture data to the engine computer, leading to a rich or lean condition and hesitation.
* Air Filter: A severely clogged air filter restricts airflow, causing a lean condition and hesitation, especially under load.
Other Potential Issues:
* Throttle Position Sensor (TPS): An inaccurate TPS signal can cause the engine computer to miscalculate fuel delivery.
* Transmission Issues (Automatic): Problems within the transmission (e.g., low fluid, worn clutches) can manifest as hesitation during acceleration. This is more likely if you feel a slipping sensation along with the hesitation.
* Exhaust Restrictions: A severely clogged catalytic converter or exhaust system can restrict exhaust flow, causing backpressure and impacting performance.
* Vacuum Leaks: Small vacuum leaks can disrupt the engine's operation and cause hesitation.
Troubleshooting Steps:
1. Check the basics: Start with the easiest checks: Inspect the air filter, check the fuel level, and visually inspect the spark plug wires for damage.
2. Diagnostic Codes: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) stored in the engine computer's memory. These codes can point to specific problem areas.
3. Fuel Pressure Test: A fuel pressure test can determine if the fuel pump and regulator are working correctly.
4. Professional Diagnosis: If you're not comfortable performing these checks, take your Mustang to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately.
It's crucial to diagnose the specific cause before attempting repairs. Working on fuel systems and ignition systems can be dangerous if not done correctly. A professional diagnosis is often the safest and most effective approach.
