The pilot/owner reported that he bought the helicopter in 2005, and that the helicopter had been out of annual inspection until May 2010. In June 2009, the helicopter was taken to an aircraft maintenance shop for its maintenance inspection; however, the pilot/owner reported that no work was done to the helicopter and that a disagreement on the component times developed. So in January 2010, he moved the helicopter back to his own shop where another mechanic completed the inspection. A month after the inspection, the pilot/owner planned to do a practice and test flight on the helicopter. He added that he did a complete run-up and that the helicopter was running fine. The pilot/owner then tried to hover-taxi the helicopter over a storage container to a helipad. As he flew past the container, the helicopter’s engine lost power and he elected to “lay” the helicopter over into a bark pile. A visual inspection by the responding Federal Aviation Administration inspectors was unable to determine any problems with the helicopter’s engine. The pilot/owner reported that once the helicopter was recovered, it appeared that a “plug” was covering the fuel tank’s vent line, and that he believed that’s why the engine lost power.