On June 26, 2005, about 1900 eastern daylight time, a Cessna 182F, N3184U, piloted by a private pilot, was substantially damaged when it nosed over during a forced landing following a loss of engine power near Lapeer, Michigan. The flight was being conducted under 14 CFR Part 91 without a flight plan. Visual meteorological conditions prevailed. The pilot reported minor injuries. The flight departed Bishop International Airport (FNT), Flint, Michigan, approximately 1845, with an intended destination of Huron County Airport (BAX), Bad Axe, Michigan. The pilot reported that the flight initially departed Door County Airport (SUE), Sturgeon Bay, Wisconsin, and landed at FNT. He then departed FNT en route to BAX. The pilot noted that the airplane was fueled with 36 gallons of 100 octane low-lead aircraft fuel at SUE. He stated that after 2 hours of total flight time since refueling at SUE, the engine "coughed" and stopped "firing." He noted that he executed a forced landing in a cornfield during which the nose landing gear collapsed and the airplane nosed over. A post-accident inspection revealed that the left fuel tank cap was not secure and was retained by the safety chain between the cap and the fuel tank filler port. The right fuel tank cap was secured to the fuel tank filler port. No fuel was present in either fuel tank. The ground under the left fuel tank cap was discolored consistent with a fuel spill over a 12-inch diameter area, to a depth of about 4 inches. A stain consistent in appearance to fuel and several "nick marks" were observed on the upper surface of the left wing aft of the fuel tank filler port. The cockpit fuel selector handle was on the "BOTH" setting when observed after the accident. The pilot stated that he visually inspected the fuel caps from the ground after refueling at SUE. He did not physically verify the security of the fuel caps.