1. Check the ignition system: This is the most probable cause of your intermittent running issues. Look at these components in this order:
* Crankshaft Position Sensor (CKP): This sensor tells the computer where the engine is in its cycle. A failing CKP sensor often leads to intermittent running, stalling, and hard starting. This is a very common failure point on older GM vehicles.
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A dirty or failing MAF sensor can cause erratic running and poor performance. Try cleaning it with MAF sensor cleaner (follow the instructions carefully).
* Ignition coil(s): These provide the high voltage spark to ignite the fuel-air mixture. Cracks or internal failures can cause misfires and intermittent running.
* Spark plugs and wires: Worn or damaged plugs and wires can also cause misfires. Inspect them visually for cracks or damage.
* Distributor cap and rotor (if applicable): Older engines might still have distributors. Look for cracks, carbon tracking, or worn contacts.
2. Check the fuel system (but not just the filter): While a clogged fuel filter is possible, other fuel system issues are more likely to cause intermittent problems:
* Fuel pump: A weak or failing fuel pump might provide enough pressure sometimes but not others, leading to the symptoms you describe. Listen for the fuel pump's whirring sound when you turn the ignition key to the "on" position (but don't crank the engine). A weak pump might only make a faint sound or not run at all.
* Fuel pressure regulator: This regulator controls fuel pressure in the system. A faulty one can cause inconsistent fuel delivery. This usually requires a fuel pressure gauge to test accurately.
* Fuel filter: This is last on the fuel system list because its failure usually causes more consistent, rather than intermittent, problems.
3. Computer/Sensors: The car's computer system might be experiencing issues.
* Check Engine Light (CEL): Is the Check Engine Light illuminated? If so, get the codes read using an OBD-II scanner. These codes can pinpoint the problem area. A 1993 LeSabre might use an older OBD-I system, which requires a different type of scanner.
Before you start:
* Safety First: Always disconnect the negative battery cable before working on any electrical components.
* Visual Inspection: Start with a visual inspection of all the components listed above. Look for anything obvious like corrosion, loose connections, or physical damage.
It's much more cost-effective to start with the cheaper and easier checks (visual inspection, checking the CEL) before tackling more involved repairs like replacing the fuel pump. If you're not comfortable working on your car yourself, take it to a trusted mechanic. Providing them with as much detail as possible about the symptoms will help them diagnose the issue more efficiently.
