On October 8, 1997, about 1730 eastern daylight time, a homebuilt RV-4, N17PQ, was substantially damaged when it impacted the ground during a forced landing on initial climb out from the Dansville Municipal Airport, Dansville, New York. The certificated private pilot/owner was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot fueled the airplane the day prior, and then flew it for 1.5 hours. He stated that there should have been about 2.5 hours of fuel remaining. The next day, he flew for 20 minutes from the Williamson-Sodus Airport, Williamson, New York, to the Dansville Municipal Airport. The pilot reported that he was on the ground for 5 minutes, making adjustments to the rudder tab. The pilot taxied to the runway, performed an engine run-up, and did not recalled any abnormalities. During the takeoff, at about 300 feet agl, the engine lost power and the propeller stopped in the horizontal position. The pilot executed a right 180 degree turn because of the surrounding terrain. Witnesses stated that the airplane impacted the ground in a 20 degree nose down attitude. The main landing gear collapsed aft, and the airplane came to a stop in about 200 feet. A Federal Aviation Administration Inspector examined the wreckage. The examination revealed that fuel was found in the carburetor bowl and in the fuel line leading to the engine driven pump. No fuel was found in the line from the engine driven pump to the carburetor. The Inspector released the wreckage to the owner/builder. The owner/builder reported to the Inspector that he disassembled the airplane and engine, and found the engine driven fuel pump incurred an internal mechanical malfunction.