* Crankshaft Position Sensor (CKP): This is a very common cause of this type of problem. When the engine heats up, the sensor can malfunction, leading to the engine stalling. The sensor itself can fail due to heat, or its wiring harness could be damaged and causing poor connection when hot.
* Coolant Temperature Sensor (CTS): A faulty CTS can provide incorrect readings to the engine control unit (ECU). This can cause the ECU to make incorrect fuel and timing adjustments, leading to stalling when the engine is hot. A bad CTS can often cause a rough idle and other driveability issues.
* Mass Airflow Sensor (MAF): While less likely to cause a complete stall, a failing MAF sensor can provide inaccurate air readings leading to poor fuel mixture at operating temperature, potentially causing the engine to sputter and die.
* Ignition Coil(s) or Ignition Wires: Heat can cause these components to fail intermittently. When the engine is hot, the failing component may not be able to provide sufficient spark to ignite the fuel-air mixture, leading to stalling.
* Wiring Harness Issues: Heat can cause poor connections or shorts within the engine wiring harness. This can affect numerous sensors and components, leading to various problems including stalling. Look for any obvious signs of melting or damage to the wiring, particularly around the engine's hotter areas.
* Fuel Delivery (despite new pump): While you replaced the fuel pump, there could still be issues with the fuel filter (clogged), fuel pressure regulator (failing), or even a leak somewhere in the fuel line that gets worse under heat.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use a code reader to scan the ECU for any stored trouble codes. This will give you clues about which system might be causing the problem. Auto parts stores often offer free code reading.
2. Inspect the CKP and CTS: Visually inspect these sensors for any signs of damage or loose connections. Consider replacing them if they appear damaged or the connectors are dirty or corroded. These are relatively inexpensive parts.
3. Check the MAF Sensor (if applicable): Clean the MAF sensor with MAF sensor cleaner (follow the instructions carefully). Replacement might be needed if cleaning doesn't help.
4. Check Fuel Pressure: Have a mechanic test the fuel pressure at operating temperature. This will rule out fuel delivery problems.
5. Inspect Ignition System: Visually inspect the ignition coil(s) and wires for any cracks or damage. Testing these components might require specialized tools.
6. Examine Wiring Harnesses: Carefully inspect the engine wiring harness for any signs of damage, melting, or chafing against hot engine parts.
Recommendation:
Since you've already done some basic work, taking it to a mechanic specializing in older vehicles might be the most efficient approach. They have the diagnostic tools and experience to pinpoint the exact cause of the intermittent stalling. Mention the symptoms and the work you've already performed to save time and money. Describing the problem as "heat soak" stalling might help them understand the situation better.
