The pilot reported he had flown the helicopter to a nearby municipal airport in order to refuel the aircraft. After topping off the 31-gallon fuel system, the airline transport rated pilot, who reported having accumulated 276 flight hours in helicopters, was westbound to a ranch located about 30 miles away, near the border. About five minutes into the flight, while the helicopter was in cruise flight, the engine "started running rough." The pilot noted that the fuel pressure had dropped to about "half of what is normal" and since the terrain on both sides of the highway were "rough and thick with mesquite trees" he elected to initiate an autorotation to the highway, which at the time was clear of vehicular traffic. During the autorotation, while approximately 50-feet above the ground, the pilot observed unmarked powerlines. The pylon attempted to maneuver the helicopter to avoid hitting the powerlines with the main rotor. The bottom wire collided with the vertical pylon supporting the tail rotor gear box which resulted in a loss of tail rotor drive. The helicopter impacted the ground while in a right drift which collapsed the right landing gear skid and rolled the helicopter. There was no fire and the pilot was able to egress the helicopter unassisted. The pilot reported that it was later determined that the electric fuel boost pump had malfunctioned. The airframe had accumulated 2,136 hours since new and the 180-horsepower engine had accumulated 704 hours since its last overhaul. At the time of the accident, the pilot reported that the weather was clear with 10 miles visibility and calm winds.