am ford newbie. changed both 3166 fuel filters. did not pull full shut off on injection pump as stated in service manual (not in cited in op manual). when i moved fuel lift pump lever no fuel moved into primary filter. loosened fuel inlet from tank into fuel transfer pump. no fuel. blew into into that fuel line. not obstructed. fuel system has two tanks. top one above engine & auxillary next to left door on cab. fuel runs into auxillary (bottom) and is pulled out of lower tank. if i did not pull fuel shut off is that what causes my prime to lose ? do i now have to fill both tanks to regain fuel to fuel transfer pump. if not how do i get fuel to transfer pump ? txs