As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT WITH BOTH ENGINE RUNNING AND PACKS ON , FA REPORTED SMELL OF GASOLINE IN AFT OF CABIN. ON GATE RETURN, APU WAS USED FOR PACKS AND FOR PACKS AND SMELL WENT AWAY. TRIED EACH ENGINE INDIVIDUALLY AFTER THAT AND SMELL DID NOT RETURN.