The pilot reported that he was enroute to his home airport when the airplane’s engine lost all power. He set up for a forced landing to a plowed field and attempted to restart the engine. The engine restarted momentarily, but then lost power again. During the forced landing, the airplane’s main landing gear impacted an irrigation ditch and the airplane nosed over and came to rest inverted. The airplane sustained substantial damage to the left wing, fuselage, vertical stabilizer and rudder. A mechanic who examined the airplane and engine after the accident confirmed continuity of the engine’s rotating components, fuel distribution throughout the engine, integrity of the ignition system, and found no evidence of any preaccident mechanical failures or malfunctions with the airplane’s engine that would have precluded normal operation. The pilot reported that before the flight, the airplane was parked on the airport ramp and the outside air temperature was near 100oF. About noon, when he went to start the airplane, the engine would not start. The pilot hangered the airplane so the engine could cool down and about an hour and a half later, the pilot started the airplane and took off. The pilot reported that he was about halfway home when the power loss occurred. The pilot also reported that the airplane had a history of vapor lock occurrences in hot weather conditions and that he thought the engine’s power loss was due to vapor lock. The loss of engine power was consistent with a fuel vapor lock occurrence.