If the hot engine stalls or will not restart, let it cool. Inspect the cooling system for causes of excessive heat, such as a faulty thermostat or cooling fan. If stalling continues, pressure-test the fuel pump and check the idle air control valve and throttle body for carbon deposits.
The owner asked what vapor lock is and how it affects an engine after the truck ran rough, stalled, and restarted several hours later. The expert explained that vapor lock occurs when overheated fuel boils in the carburetor bowl or fuel pump and stops flowing, causing stalling or hard starting, especially in hot weather. The expert advised cooling the engine and checking for overheating causes, while also noting a failing fuel pump or carbon deposits in the idle air control valve or throttle body as possible causes.
