The airplane impacted terrain during a forced landing following a total loss of engine power. The pilot reported that during the preflight inspection he visually inspected the fuel tank and no fuel contamination was detected from a gascolator fuel sample. The pilot performed three landings, but while on the downwind leg for the fourth landing "the engine abruptly stopped." Best glide speed was established and the airplane was maneuvered toward the runway for landing. The pilot reported that he "confirmed that carb heat was off and mixture full, rocked the wings and switched mags off and then on, in an attempt to restart the engine." The airplane "just cleared" the perimeter fence and touched down short of the runway in a ditch. The right main gear subsequently separated and the airplane rolled inverted. An on-scene inspection of the airplane indicated that there was sufficient fuel available in the fuel tank and a gascolator fuel sample was free of water and particulate contamination. Examination of the carburetor revealed that the carburetor fuel flow valve would stick in the closed position.