On October 14, 2003, at 1800 eastern daylight time, a Cessna A185E, N3399L, contacted rough terrain during an off airport forced landing following a loss of engine power about 10 miles east of Cedarville, Michigan. The commercial pilot was not injured. The airplane received substantial damage. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The flight originated from the Albert J. Lindberg Airport, Cedarville, Michigan, at 1750. The pilot reported he had flown 4.1 hours since the airplane was last fueled and he calculated that he had 11 gallons of fuel remaining for the 15 minute flight. He reported that approximately 10 minutes after takeoff, the engine lost power. The pilot stated he activated the fuel pump and the engine momentarily gained power. He stated the fuel selector was on "Both", the left fuel tank was indicating empty, and the right fuel tank was varying between 1/8 and 1/4 full. The pilot reported he was over a heavily wooded area when the engine lost power and he picked out a small clearing in which to land the airplane. He stated the clearing contained logs, rocks, stumps, and ruts, which resulted in the airplane stopping "very quick" after touchdown. The pilot reported he exited the airplane and walked a couple miles out of the woods to get help. The company that recovered N3399L from the woods reported they drained 12 gallons of fuel from the right fuel tank and a little over 2 gallons of fuel from the left fuel tank. They also reported the fuel selector was positioned on "Both" when they saw the airplane. The pilot also stated the he always flew the airplane with the fuel selector on "Both." Post accident inspection of the airplane and engine by an airworthiness inspector from the Federal Aviation Administration failed to reveal any mechanical failure/malfunction that would have resulted in the loss of engine power. The engine driven fuel pump was removed from the engine. The pump operated normally when tested.