The pilot was departing on an early morning flight and said that he performed his preflight and pretakeoff checklists. During the takeoff roll, he realized that he had forgotten to switch the fuel tank from the left tank (containing less than 1 gallon of fuel) to the right tank (containing about 35 gallons of fuel). The pilot switched the fuel tank selector from the left tank to the right tank during the takeoff roll, and during the initial climb, the engine sputtered and lost power. The pilot force-landed the airplane off the end of the runway. During the forced landing, the airplane collided with a fence post and incurred substantial damage to the left wing. Following the accident, a Federal Aviation Administration inspector examined the fuel transfer system on the airplane and successfully test ran the engine. No mechanical anomalies were identified.