Just prior to departure, the fuel tanks were filled. The pilot stated that he drained both tanks after refueling by using the strainer pull handle in the cockpit with the selector positioned to each tank. However, he did not drain the individual tank sumps. After takeoff, he climbed to 8000 ft and was in normal cruise, when the engine lost power. He noted that the fuel pressure had dropped to near zero and he was unable to restore the pressure or start the engine. While landing in winds gusting to 22 kts, he cleared power lines, but just before touchdown, the aircraft struck a tree. No discrepancies of the aircraft were found except water in some locations of the fuel system. The flight manual noted that freezing temperatures were common above 8000 ft and if encountered, condensed water in the lines would freeze and cause fuel starvation; therefore, sumps should be drained before each flight and after each refueling. It also warns to allow 5 minutes for water and sediment to settle in the tanks and fuel selector valve before taking samples. Temperature at 8000 ft approximately 28 degrees.