* Crankshaft Position Sensor (CKP Sensor): This sensor is crucial for the engine's timing. If it gets too hot, it can malfunction and fail to send the proper signal to the computer, preventing starting. Once it cools down, it works again. This is a very common culprit for this type of starting problem.
* Ignition Coil: Similar to the CKP sensor, the ignition coil can fail when it gets hot. It's responsible for providing the high voltage needed to ignite the spark plugs. Heat can cause it to weaken or fail temporarily.
* Distributor (if equipped): Older Rangers may have distributors. Issues within the distributor, such as worn-out points (if it uses them) or a failing pickup coil, could be exacerbated by heat.
* Fuel Pump Relay: While less likely to be directly heat-related, a failing fuel pump relay could be intermittently failing when hot. The half-hour cool-down period might allow it to recover.
* Mass Airflow Sensor (MAF Sensor): A faulty MAF sensor can cause erratic fuel delivery. While not directly a heat problem *in the sensor itself*, heat from the engine bay *can indirectly affect its readings*, leading to poor starting when hot.
* Engine Coolant Temperature Sensor (ECT Sensor): A faulty ECT sensor provides inaccurate readings to the engine computer. The computer uses this information to adjust fuel delivery and timing. An incorrect reading due to a faulty sensor (or even a sensor that's become temporarily unreliable due to heat) can prevent starting when hot.
Troubleshooting Steps:
1. Check for error codes: Use an OBD-II scanner (if your Ranger has it; 1994 might be borderline) to read any diagnostic trouble codes (DTCs) stored in the computer. This could point directly to the faulty component.
2. Inspect the CKP Sensor: Locate the CKP sensor (usually near the crankshaft). Visually inspect it for any damage or loose connections. If it's easily accessible, you might try gently cleaning it with electrical contact cleaner. However, it's probably best to replace it if suspected.
3. Check the ignition coil: Visually inspect for cracks or damage. Testing an ignition coil requires a multimeter, and if you're not comfortable doing electrical testing, take it to a mechanic.
4. Consider the distributor (if applicable): If your Ranger has a distributor, it might require professional attention. Internal components can be difficult to diagnose without specialized tools.
5. Listen carefully while cranking: Does the engine sound weak or hesitant, suggesting a lack of spark or fuel? A lack of cranking power itself might indicate a bad battery or starter.
Recommendation:
Given the heat-related nature of the problem, starting with the CKP sensor and the ignition coil is your best bet. These are relatively inexpensive parts and relatively straightforward to replace (though you'll need some basic mechanical skills). If replacing these parts doesn't solve the problem, you'll likely need to consult a mechanic for more in-depth diagnosis. Don't attempt to replace the fuel pump or other more complex components yourself unless you have experience working on cars.
