The pilot with three passengers planned to depart and return on a cross-country flight. The pilot stated that the airplane's left fuel tank was filled to an inch below the collar, and the right fuel tank was filled to two inches below the collar. He estimated that the airplane had 40-45 gallons of fuel on board, with a planned en route time of 57 minutes, and about a 10 knot tailwind. Once at a cruise altitude of 7,500 feet, he set the manifold pressure at 21 inches and engine rpm at 2,300 for a fuel burn of 12.3 gallons/hr per the pilot operating handbook. The pilot reported for the return leg he again visually checked the fuel level in each tank. He estimated 12-15 gallons in the left tank and 10 in the right, for a total of 22-25 gallons. The pilot added that fuel burn seemed normal and he decided not to add fuel, he also stated that estimations are not an accurate science and that a fuel stick was not provided to confirm the fuel level. After departing for the return flight, he switched fuel tanks from the left side to the right side. About 15 minutes later, the pilot noticed a reduction in power and switched back to the left side fuel tank. Engine power was restored, and the pilot stated that he did not feel that the fuel had been exhausted from the right side based on his calculations. A few minutes later, the engine lost power and the pilot preformed a forced landing to a construction site. A post-crash examination of the airplane revealed substantial damage to the airplane's fuselage and left wing during the forced landing. Additionally, the Federal Aviation Administration inspector reported that the fuel tanks were empty and were not breached in the accident.