On April 2, 1995, at 1336 eastern daylight time, a Piper PA-J3-C65, N70234, lost total engine power during takeoff climb from runway 18 at the Bayport Aerodrome, Bayport, New York. The airplane struck a fuel truck and hangar while being maneuvered back to the departed runway. The non certificated pilot was seriously injured. The airplane was destroyed. Visual meteorological conditions prevailed. The local flight was conducted under 14 CFR Part 91. According to a Federal Aviation Administration (FAA) Safety Inspector, the pilot reported that during initial climb, about 200 to 300 feet above the ground, the airplane's engine "coughed" and then lost total power. The pilot reported he turned the airplane 180 degrees back toward the departed runway and during the maneuver the airplane's right wing impacted a fuel truck. The airplane impacted the fuel truck and continued into a brick hangar. Postaccident examination of the airplane revealed the fuel flow selector valve was in the OFF position. Fuel was found in the engine's gascolator and throughout the engine fuel lines. The airplane's three fuel tanks were breached during the accident. Witnesses at the airport reported to a Federal Aviation Administration Inspector that the pilot "...topped off the airplane..." prior to the accident flight. No other airframe or engine anomalies were noted. The pilot received a National Transportation Safety Board (NTSB) Pilot/Operator Aircraft Accident Report, Form 6120.1/2, but did not complete and return it to the Safety Board.