On August 1, 1993, about 2030 central daylight time, a Cessna 152 airplane, N49899, sustained substantial damage during a forced landing to a field near the Marion Airport, Marion, Iowa. The commercial pilot and sole passenger aboard were not injured. The personal flight operated without flight plan under 14 CFR Part 91 in visual meteorological conditions. The flight departed Hannibal, Missouri, about 1830. The pilot reported a loss of engine power following an aborted landing approach at Marion. The airplane nosed over during the subsequent forced landing in a field. Examination of the airplane revealed fuel in the fuel line, but only one gallon(total)of fuel was drained from the fuel tanks. The airplane operating handbook lists the total fuel capacity as 26 gallons, with 1.5 gallons unusable. No postaccident mechanical anomalies were discovered with the engine or fuel system.