On October 13, 1995, at 1830 hours Pacific daylight time, a Cessna 140, N1782V, collided with the ground following a loss of engine power during the takeoff initial climb at the Main Prairie airport, Dixon, California. The aircraft was owned and operated by the student pilot and was engaged in touch-and-go traffic pattern operations. Visual meteorological conditions prevailed and no flight plan was filed. The aircraft incurred substantial damage. The student pilot, the sole occupant, sustained minor injuries. The local area solo instructional flight originated at the Main Prairie airport on the day of the accident at 1800. In a telephone interview, the pilot reported that he was performing touch-and-go pattern operations on runway 32. He said he noted that the fuel level in the left tank was down to 1/4 shortly after lift-off. The pilot then switched the fuel selector valve from the left tank to the right and the engine sputtered and lost power. The aircraft altitude was insufficient to return to the runway and the pilot landed in a corn field, damaging the fuselage and wings. The pilot said that after the accident he noticed that the fuel valve handle was positioned 1/2 inch beyond the right tank index point. The aircraft sustained substantial damage to the engine mount, propeller, the forward engine cowling and airframe aft of the firewall. FAA inspectors conducted an on-scene investigation, both at the accident site and after recovery to a salvage yard. The inspectors found that there was 2 1/2 gallons of fuel in the right wing tank and 3 1/2 gallons in the left wing tank. They stated that no water contamination was detected. When the gascolator was inspected, it was found to be free of visible obstructions and the screen appeared new. When investigators opened the carburetor they noted a small amount of debris in the bowl. The individual debris particles were noted to be large enough to obstruct the flow of fuel to the main jet. Further inspection revealed there was a fragment of debris in the orifice of the main jet blocking it about 60 to 70 percent. Microscopic inspection of the small piece of debris did not reveal its composition or origin.