At 20:00 PST, a Piper PA-38-112 lost power and was damaged landing on a country road near Kern Valley Airport. The two occupants were not injured. The flight had originated from Las Vegas at 16:00 and was scheduled to terminate at Fresno, Calif. The pilot said he planned to stop for fuel at Inyokern, Calif. The pilot reported that approximately 45 minutes into the flight his passenger became agitated and wanted to land. He diverted to Trona, Calif., approximately 25 miles from Inyokern, to take care of his passenger. There were no fuel services at Trona and he took off and continued the flight to Fresno, without stopping at Inyokern to refuel. The pilot reported to flight following that he was low on fuel and asked for vectors to the nearest airport, which was the unlighted Kern Valley Airport. The pilot descended to 1,000 feet agl to locate the airport. The airplane ran out of gas and the pilot landed on a road, at which point the wing struck a road sign.