crank no start after driving a short time; will restart if fuel pressure relieved at fuel rail

Crank no start condition occurs after vehicle reaches operating temperature and driven only short distance (less than 10 miles). After much testing during complaint occurrence, it was found that if fuel shrader valve at test pressure port is held open and fuel allowed to escape at fuel rail while cranking, engine will start. What are the possibilities that would allow such action (albeit, dangerous action) to have the vehicle start and run when it would not do so otherwise unless vehicle engine temperature was allowed  to cool below normal operating temperature. Please, please help!