The pilot reported that, during his preflight inspection, he perceived that both fuel tanks were full. Based on previous flights, full fuel tanks allowed for about 5 hours of flight endurance. About 4 hours after departure, the pilot noticed a low fuel quantity on the cockpit gauges but continued the flight toward the planned destination airport. Several minutes later, the engine lost power, and the pilot performed a forced landing to a field. The airplane impacted a power line and nosed over, which resulted in substantial damage to the right wing and fuselage. Postaccident examination of the airplane revealed that the fuel tanks contained no usable fuel. Following the accident, the pilot stated he should have landed earlier to refuel. He also discovered that a co-owner had not filled the fuel tanks after the previous flight, as he had expected.