(Adds details, background) By Valerie Insinna WASHINGTON April 5 (Reuters) - Boeing Co said on Wednesday it had restarted deliveries of its widebody 767 after a three-month pause caused by supplier quality issues. The U.S. planemaker was forced to halt deliveries of the 767F freighter and KC-46 tanker earlier this year after it discovered center fuel tanks made by a supplier were not properly sealed. Boeing declined to comment on when 767 deliveries restarted, but flight data shows it handed over a 767F freighter to FedEx on March 24.