On February 10, 2001, at 1015 eastern standard time, a Jack McDaniel, Rans S-12, N823S, collided with the ground while attempting to takeoff from a plowed field, near Homestead, Florida. The experimental airplane was operated by the private pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The pilot sustained serious injuries; the passenger was not injured and the airplane was substantially damaged. The flight originated from Homestead, Florida, at 1000. According to the passenger, the pilot's wife, shortly after takeoff from Homestead Regional Dade County Airport, the engine lost power. The pilot selected a plowed field for an emergency landing. After making a safe landing, the pilot examined the engine and felt that he could attempt to takeoff again. The pilot stated that after takeoff he reduced flaps from two notches to one, and the airplane banked to the right. He applied left rudder and aileron to correct the bank, and then retarded the throttle. The airplane then entered a stall/ spin, and collided with the ground. The post-accident examination and functional check of the engine failed to disclose a mechanical problem. However, the examination of the fuel system revealed a significant amount of contamination in the main fuel filter, fuel drains, fuel pump, filter elements, and carburetor bowls. The fuel tanks also show signs of a varnish solution normally associated with stale automotive fuel. The pilot's wife reported that her husband refueled the airplane using a bucket, and he performed his own maintenance on the airplane. The pilot was not a Federal Aviation Administration Certified Airframe and Powerplant Mechanic.