A 2,350-hour commercial pilot completed a 393-nautical mile cross-country flight, and was preparing to land at his destination airport when he experienced a total loss of engine power while on final approach. The single-engine airplane landed short of the 3,960-foot long runway, slid, and came to rest about 100 feet short of the runway threshold. An FAA inspector, who examined the airplane, reported that the engine firewall was wrinkled and confirmed that there was fuel present in the left fuel tank. He added that witnesses reported observing fuel draining from the right wing after the accident. The pilot reported that the power loss was the result of a faulty fuel pump. Examination of the fuel pump and engine by an airframe and power plant mechanic did not reveal any anomalies or mechanical deficiencies. The reason for the loss of engine power could not be determined.