1. Cooling System Problems:
* Overheating: This is the most common cause. If the engine overheats, it can cause the computer to shut down the engine to prevent damage. Check your coolant level, look for leaks (especially around the radiator, hoses, and water pump), and ensure the radiator fan is working correctly (it should come on when the engine reaches a certain temperature). A failing thermostat could also be preventing proper cooling. A clogged radiator or a failing water pump are also possibilities. *Get this checked first.*
* Low Coolant: Even a small leak can cause overheating, leading to stalling. Top up the coolant (after letting the engine cool completely) and check for leaks. Use the correct 50/50 mix of coolant and distilled water.
2. Ignition System Issues (Heat Sensitivity):
* Ignition Coil: Heat can cause the ignition coil to malfunction, leading to misfires and stalling. These often fail when hot, working fine when the engine is cold.
* Distributor Cap and Rotor (if applicable): Cracks or worn components in the distributor cap and rotor can cause intermittent ignition problems, especially when hot. High temperatures can exacerbate existing issues.
* Spark Plugs and Wires: Worn or damaged spark plugs and wires can misfire more frequently when hot.
3. Fuel System Problems (Heat Sensitivity):
* Fuel Pump: A weak fuel pump might struggle to deliver enough fuel when hot, leading to stalling. The pump might be struggling to maintain pressure at higher operating temperatures.
* Fuel Filter: A clogged fuel filter can restrict fuel flow, worsening under heat.
4. Sensor Issues:
* Mass Airflow Sensor (MAF): A faulty MAF sensor can provide inaccurate readings to the engine computer, leading to poor fuel mixture and stalling. Heat can affect its accuracy.
* Temperature Sensors: The engine's temperature sensor(s) might be providing incorrect readings to the computer, causing it to adjust the fuel mixture improperly.
5. Electrical Issues:
* Wiring Harness: Heat can damage wiring, leading to intermittent electrical problems. Look for any obvious signs of melting or damage in the engine bay.
Troubleshooting Steps:
1. Check coolant level and look for leaks. This is the most crucial first step.
2. Check the radiator fan. Does it come on when the engine is hot?
3. Have the cooling system pressure tested. This will pinpoint leaks you might not otherwise see.
4. Inspect spark plugs, wires, distributor cap, and rotor (if equipped). Look for cracks, burning, or wear.
5. Check the fuel pressure. This requires a fuel pressure gauge.
6. Have the MAF sensor tested.
7. Scan for Diagnostic Trouble Codes (DTCs). A mechanic can use an OBD-I scanner (for your 1993 Tempo) to check for stored codes that might pinpoint the problem.
Important Note: Diagnosing a stalling issue accurately requires a methodical approach. Trying to fix it yourself without the right tools and knowledge could lead to further damage. It's best to consult a qualified mechanic, especially given the age of the vehicle. They have the diagnostic tools and expertise to pinpoint the cause efficiently and safely.
