At about 1655 eastern time, a homebuilt RV-6A crashed approximately 715 feet from the approach end of runway 31 after losing engine power during a practice instrument approach. The pilot suffered minor injuries. The pilot said he had switched tanks about an hour into his flight, and about 15 minutes after switching tanks the engine lost partial power. He applied more throttle and initiated the instrument approach. During his prelanding checklist, he turned on the auxiliary pump, applied carb heat and reduced power. The engine then quit smoothly as if the mixture had been pulled. He tried to restart the engine unsuccessfully. When he realized he would be unable to make the runway, he lowered full flaps and slowed to just above stall speed. The airplane came to rest inverted and the pilot evacuated the airplane by cutting a portion of the canopy with a survival tool.