not too clued up on "yank tanks" but normal engineering logic apply's, first have you checked the pump supply fuse? it is very unlikely that someone backing into the vehicle would trip any safety switch unless the damage was extreme to your vehicle, has it got an immobilizer thats not switched off by the correct (manufacturers) method ie key pad, alarm fob or key transponder, other than that if all checks are good and there is a supply to the pump replace the pump!
nigel
March 2008