On August 31, 1998, about 1153 eastern daylight time, a Piper PA-34-200, N15541, registered to Nurnberg Family Enterprises, Inc., crashed while on approach to land at Daytona Beach International Airport, Daytona Beach, Florida, while on a Title 14 CFR Part 91 instructional flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the commercial-rated flight instructor and private-rated dual student received minor injuries. The flight originated from Daytona Beach, the same day, about 1035. The flight instructor stated that the dual-student flew a normal approach to runway 7 left. During the landing flare, the left engine quit. The dual-student did not recognize the left yaw caused by the failed left engine and initiated a go-around by applying full power on the operative engine and rotating the nose to a climb attitude. The aircraft began to roll to the left and the instructor attempted to gain control of the aircraft from the dual-student, who was frozen on the controls. The instructor placed the left propeller in the feathered position and attempted to perform a single engine go-around. The dual-student finally let go of the controls and as the instructor was attempting to reduce engine power and make a forced landing in the grass adjacent to the runway, the left wing struck the ground and the aircraft spun around, coming to rest. The dual-student stated he performed a normal approach to runway 7 left. As he flared for landing, the aircraft ballooned. He applied power to increase airspeed because the aircraft was below Vmc speed. He noticed the aircraft was yawing to the left, which his instructor took as a sign that the left engine had failed. The instructor placed the left propeller in the feathered position and attempted to regain control of the aircraft. The aircraft hit the ground with the left wing and spun around, coming to rest. Postcrash examination of the aircraft's fuel system and left engine controls showed no evidence of mechanical failure or malfunction. The left engine and propeller were removed from the aircraft and mounted on an engine test stand. The propeller was in the feathered position. The engine was started and operated to full power with no evidence of mechanical failure or malfunction. The engine-driven fuel pump was found to have a small leak in the diaphragm, which was draining overboard. The engine was operated to full power using only the engine-driven fuel with no loss of power.