On May 14, 1995, at 1100 mountain daylight time, a Grumman/Schweizer G-164A, N9506, was substantially damaged during a forced landing, approximately 14 miles north of Joes, Colorado. The pilot was not injured. Visual meteorological conditions prevailed for this 14 CFR Part 137 flight. No flight plan was filed. The pilot stated that the engine quit while on an aerial application run and he conducted a forced landing in a soft field. The aircraft nosed over during landing roll. Examination of the aircraft by a repair facility provided information that the engine quit due to fuel exhaustion. Examination of the fuel system by the repair facility provided evidence that the fuel gauge, which is a float type gauge, read 15 gallons when the tanks were empty. The pilot provided information that the fuel gauge and measuring system components were original equipment and had approximately 5,311 hours in service with no overhaul, which is not required. The pilot also provided information that he had not conducted any fuel consumption calculations and relied on his fuel gauge.