Fuel System:
* Fuel Pump: A failing fuel pump may not be delivering enough fuel to keep the engine running. This is a common cause of the described symptom. The pump might be weak, failing completely, or have a blockage.
* Fuel Filter: A clogged fuel filter restricts fuel flow, leading to engine shutdown.
* Fuel Pressure Regulator: This component regulates fuel pressure. A faulty regulator could cause insufficient pressure or leaks, resulting in the engine stalling.
* Clogged Fuel Injectors: Dirty or clogged fuel injectors prevent proper fuel delivery.
* Fuel Pump Relay: The relay might be failing, preventing power from reaching the fuel pump.
Ignition System:
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position. A faulty CKP sensor will prevent proper ignition timing and cause the engine to stall.
* Camshaft Position Sensor (CMP Sensor): Similar to the CKP sensor, a faulty CMP sensor will disrupt ignition timing.
* Ignition Coil: A failing ignition coil may not provide sufficient spark to all cylinders, leading to stalling.
* Distributor (if applicable): Older Cadillacs might have distributors. Issues within the distributor, such as worn points or a bad cap/rotor, can disrupt spark delivery.
* Ignition Switch: A faulty ignition switch might not be providing consistent power to the ignition system.
Other Potential Causes:
* Computer (PCM/ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) could be malfunctioning, causing various problems, including stalling. This is a more complex issue to diagnose.
* Throttle Position Sensor (TPS): A faulty TPS might be sending incorrect information to the PCM, leading to improper fuel delivery and stalling.
* Mass Airflow Sensor (MAF Sensor): A bad MAF sensor gives the computer incorrect information about the air intake, leading to poor fuel mixture.
* Security System: Some older cars had rudimentary security systems that could prevent starting or cause stalling if there's a problem with the system.
* Low Battery Voltage: Though less likely to cause an immediate shutdown after a few seconds, a very weak battery could still contribute.
Troubleshooting Steps (in order of relative ease):
1. Check the basics: Ensure the battery is charged and the connections are clean and tight.
2. Listen for the fuel pump: When you turn the key to the "on" position (but not starting), you should hear a brief hum from the fuel pump. If not, that's a strong indicator of a fuel pump problem.
3. Check fuel pressure: This requires a fuel pressure gauge and is best left to a mechanic unless you have experience.
4. Inspect wiring and connections: Look for any damaged, loose, or corroded wiring, especially in areas related to the fuel system and ignition system.
5. Have a mechanic perform a diagnostic scan: A mechanic can use a scan tool to read diagnostic trouble codes (DTCs) from the PCM, which will pinpoint potential problems.
Given the age of the car, several components might be worn out or failing. A professional diagnosis is highly recommended to identify the root cause efficiently and safely. Attempting to diagnose and fix this without the right tools and knowledge could lead to further damage or injury.
