Fuel System:
* Fuel Pump: A weak or failing fuel pump can't deliver enough fuel to sustain running. Listen for the pump's whirring sound when the key is turned to the "on" position (before cranking). Lack of sound indicates a possible problem.
* Fuel Filter: A clogged fuel filter restricts fuel flow. This is a cheap and easy part to replace.
* Fuel Injectors: Clogged or faulty injectors may not deliver the proper amount of fuel. This requires more advanced diagnostics.
* Fuel Pressure Regulator: A malfunctioning regulator can cause incorrect fuel pressure in the system.
Ignition System:
* Distributor Cap and Rotor: Cracked, corroded, or worn components can disrupt the spark delivery. Inspect for visible damage.
* Spark Plugs and Wires: Worn, fouled, or damaged spark plugs and wires can prevent a consistent spark. Check for gaps, corrosion, and cracks.
* Ignition Coil: A weak or failing ignition coil won't produce enough voltage for a strong spark.
* Ignition Module (Electronic Ignition Control): This component is crucial for the ignition system's timing and spark generation; failure can prevent the engine from running consistently.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position. A faulty CKP sensor can prevent the engine from starting or running consistently.
Other Potential Causes:
* Air Intake System: A large air leak in the intake system (vacuum leak) can disrupt the air/fuel mixture, causing poor running or stalling. Check all hoses and connections for cracks or looseness.
* Throttle Body: A dirty throttle body can cause idling problems and affect drivability.
* Computer/ECM (Engine Control Module): A faulty ECM can cause numerous issues, including intermittent running. Diagnostics are needed to test this.
* Alternator: While it doesn't directly stop the engine running *immediately*, a failing alternator will eventually drain the battery, leading to the engine dying after a short time.
* Battery: A weak battery might crank the engine, but it may not have enough power to keep it running consistently, especially if the engine's electrical demand is high (like a failing alternator).
Troubleshooting Steps:
1. Check the basics: Start with the simple things – check the battery, fuel level, and visually inspect the spark plugs and wires.
2. Listen for the fuel pump: As mentioned above, listen for the fuel pump's whirring sound when the key is turned to the "on" position.
3. Check for codes: If your 1985 Z28 has a diagnostic port (check your owner's manual), you might be able to retrieve diagnostic trouble codes (DTCs) which can pinpoint the problem.
4. Consult a repair manual: A Haynes or Chilton repair manual for your specific vehicle will provide detailed diagrams and troubleshooting guides.
5. Seek professional help: If you're not comfortable working on your car, take it to a qualified mechanic. They have the tools and experience to diagnose and repair the issue efficiently.
It's impossible to pinpoint the exact cause without more information or a hands-on inspection. The steps above should help you narrow down the possibilities. Remember to always prioritize safety when working on your vehicle.
