On October 4, 2001, about 2000 eastern daylight time, a homebuilt CGS Hawk A, N3963W, was substantially damaged during a forced landing to a private airstrip near Fayetteville, Ohio. The certificated private pilot was seriously injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. According to the pilot, he had departed from the private airstrip, and climbed to traffic pattern altitude. At altitude, he encountered gusting wind conditions and elected to land. On the base leg of the approach, the engine lost power. The pilot performed a forced landing to an up-sloping field, where the airplane touched down hard, and came to rest upright. Inspection of the wreckage by a Federal Aviation Administration (FAA) inspector revealed that the cockpit area had separated from the remainder of the fuselage. Inspection of the engine revealed that a thin rubber line, which connected the engine driven vacuum pump to the pneumatic fuel pump, was dry rotted and broken off from it's connection at the pneumatic fuel pump. The FAA inspector also noted that the fuel supply was located below the area where the engine was mounted onto the airframe. The pilot further stated that he had completed most of the airplane's annual inspection, and performed an engine run-up prior to the accident flight. No abnormalities were noted.