The pilot reported that while in cruise flight at 1,500 ft mean sea level (msl), the engine lost power and the pilot observed a low fuel pressure indication. He engaged the manual fuel pump, and engine power was briefly restored. He turned the airplane back toward the departure airport, but the engine power remained unreliable. The pilot selected a highway for an emergency landing and landed as close to the right side of the westbound lane as practical to maintain separation from vehicular traffic. During the landing rollout, the right wing struck a road sign which pulled the airplane sharply to the right. The main landing gear collapsed, and the airplane came to rest in a ditch. The right wing sustained substantial damage. The airplane was examined after the accident. The fuel tanks were intact and no fuel was present. The pilot reported that he checked his fuel totalizer before the flight but was distracted by a conversation and did not verify the fuel quantity visually. He reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.