Fuel System:
* Fuel Pump: A failing fuel pump might not deliver enough fuel pressure to the engine, leading to stalling, especially under load. Check fuel pressure with a gauge.
* Fuel Filter: A clogged fuel filter restricts fuel flow. It's inexpensive and easy to replace.
* Fuel Injectors: Clogged or faulty injectors can cause inconsistent fuel delivery, leading to stalling. This often requires professional diagnosis and cleaning or replacement.
* Fuel Pressure Regulator: A malfunctioning regulator might deliver incorrect fuel pressure.
* EGR Valve: A faulty Exhaust Gas Recirculation valve can lead to a lean fuel mixture and stalling, particularly at idle.
Ignition System:
* Distributor Cap and Rotor: Worn or cracked distributor cap and rotor can cause poor spark delivery, resulting in misfires and stalling.
* Ignition Coil: A weak or failing ignition coil won't provide sufficient spark to ignite the fuel-air mixture.
* Spark Plugs and Wires: Worn, fouled, or damaged spark plugs and wires can prevent proper ignition.
* Ignition Module (TFI Module): A common failure point in these cars. A faulty TFI module can prevent the ignition system from functioning correctly.
Sensors:
* Throttle Position Sensor (TPS): A faulty TPS provides incorrect information to the engine computer, leading to poor fuel delivery and stalling.
* Mass Airflow Sensor (MAF): An inaccurate MAF sensor reading can cause the engine to receive an incorrect air/fuel mixture.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the position of the crankshaft. A faulty sensor can prevent the engine from starting or cause it to stall.
* Oxygen Sensor (O2 Sensor): While less likely to cause immediate stalling, a bad O2 sensor can lead to poor fuel mixture over time and contribute to erratic running that may eventually result in stalling.
Vacuum Leaks:
* Vacuum Hoses: Cracks or disconnections in vacuum hoses can disrupt the operation of various engine components, leading to stalling. Inspect all vacuum lines carefully.
Other Possibilities:
* Alternator: A failing alternator might not charge the battery, leading to stalling once the battery is drained.
* Battery: A weak or dying battery can also cause stalling.
* Computer (PCM): Although less common, a failing engine control module can cause a variety of problems, including stalling. This is usually a more difficult diagnosis.
* Wiring Issues: Corrosion or damaged wiring can disrupt the electrical signals to various components.
Troubleshooting Steps:
1. Check for obvious things: Low fuel, loose battery terminals, obvious vacuum leaks.
2. Listen to the engine: Unusual noises can offer clues.
3. Check engine codes: Use an OBD-I code reader (if possible) to diagnose any stored trouble codes. Note that 1987 OBD-I systems are very basic compared to modern OBD-II.
4. Start with the simple, cheap fixes: New spark plugs, wires, distributor cap and rotor, fuel filter.
5. Systemic approach: Start with the fuel system (pressure test), then ignition, then sensors, and finally vacuum.
It's crucial to systematically check these areas. If you're not experienced with automotive repair, it's best to consult a qualified mechanic, especially given the age of the vehicle. A proper diagnostic is essential to pinpoint the exact cause of the stalling problem.
