According to the pilot's statement, the accident flight was the first flight after a major rebuild of the airplane. After completing ground runs on the engine, the pilot and passenger departed the airport for a test flight. During the initial climb, approximately 600 feet above the ground, the engine lost power. The pilot elected to land in a snow covered field, and during the landing the airplane nosed over. Substantial damage was sustained to both the front and rear lift struts on the right wing. A postaccident inspection of the fuel system by the pilot, who is also the mechanic that oversaw the rebuild of the airplane, revealed a flap of rubber inside a flexible fuel hose that was of significant size to restrict fuel flow to the engine. The fuel hose was fabricated by the airplane owner, under the supervision of the mechanic. The fuel hose was fabricated out of flexible automotive hydraulic line, not approved aircraft-grade fuel hose.