Here are several potential causes to investigate, focusing on areas that mimic vapor lock symptoms:
* Fuel Pump: A weak or failing fuel pump might not deliver enough fuel pressure, especially under load or when the engine's hot. This can lead to stalling. Testing fuel pressure is crucial.
* Fuel Pump Relay: The relay controls power to the fuel pump. A faulty relay can intermittently cut power, causing the engine to die.
* Clogged Fuel Injectors: Dirty injectors can restrict fuel flow, leading to inconsistent running and stalling. A fuel injector cleaning or replacement might be needed.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position. A faulty CKP sensor can cause the engine to stall or not start.
* Mass Airflow Sensor (MAF Sensor): This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can cause the engine to run lean, leading to stalling.
* Ignition System: Problems with the ignition coil, spark plugs, or wires can cause misfires and stalling. Worn spark plugs are a common issue in older vehicles.
* Heat Soak (Contributing to Vapor Lock Feeling): While true vapor lock is less likely, excessive heat in the engine bay (especially in hot climates) can cause fuel to vaporize more readily, leading to a similar symptom. Consider whether it stalls more frequently after a period of driving. Improved engine bay ventilation might help.
* Evaporative Emission System (EVAP): Problems in the EVAP system (which controls fuel vapor) can sometimes cause drivability issues. A leak or malfunctioning component could be contributing.
Troubleshooting Steps:
1. Check Fuel Pressure: This is the most important initial step. A mechanic can easily test the fuel pressure to see if it's adequate.
2. Inspect Fuel Lines: Look for any cracks, kinks, or damage in the fuel lines.
3. Check the Fuel Pump Relay: Try swapping the relay with a known good one (from another system, if possible).
4. Scan for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to check for any stored trouble codes. These codes can pinpoint potential problems.
5. Inspect and/or replace the Spark Plugs and Wires: This is a relatively inexpensive and easy maintenance item that often solves various problems.
It's unlikely that replacing the fuel filter three times is the solution if the problem persists. You need a more thorough diagnosis focusing on the areas listed above. A qualified mechanic can perform these tests and determine the root cause efficiently. Don't keep throwing parts at it without a proper diagnosis; you'll waste money and time.
