On August 7, 1998, about 1103 eastern daylight time, a Mooney M20A, N8385E, collided with the ocean during a visual approach to the Marathon Airport, Marathon, Florida. The airplane was operated by the owner/pilot, under the provisions of Title 14 CFR Part 91, and visual flight rules (VFR). Visual meteorological conditions prevailed, and a VFR flight plan was filed for the personal flight. The private pilot and his pilot-rated passenger were seriously injured, and the airplane was substantially damaged. Origination of the flight was Warner Robins, Georgia, about 0700, on the same day. According to the pilot, he refueled prior to departure and verified the fuel tanks were full. He climbed to 7,500 feet and leaned the mixture for the flight. He used the fuel in two of the fuel tanks during the flight, and was operating off the third fuel tank as he approached Marathon. Upon turning final for runway 9 at the Marathon Airport, with the landing gear extended, the engine quit. He stated he turned left to avoid buildings, then collided with the water seconds later. Subsequently, during an examination of the engine, the fuel pump diaphragm was found to be perforated, which would result in pumping fuel overboard, during flight. The FAA inspector who examined the airplane maintenance records reported that the fuel pump had not been inspected nor repaired during the last engine overhaul. In his statement, the pilot indicated that at one point during the flight, at a time and position that could not be recalled, he and his wife smelled fuel. The odor lingered for a short while and they forgot it.