When I bought mine I got the same thing after I filled up past 3/4. I dropped the tank and found the locking ring that holds down the fuel pump to be loose. Since I already bought a new locking ring and seal I just cleaned all the dirt out (and there will be dirt and rocks piled up in there.) and installed the new stuff after inspecting the pump and filter sock. Havent had a problem since then. Parts cost me around $25 so it wasnt too bad, but it is labor intensive especially if you have the factory hitch which forces you to take the bumper cover off to get to those last two bolts. Oh and if you replace the seal make sure to lube it up real good along with the nut threads with a soapy water solution so you dont tear the seal.
Bear - 1999 Jeep Grand Cherokee Laredo - 250,000 Miles, BDS 2" lift, Overland rock rails, Dynomax cat back exhaust, 245/75/16 Kumho KL78's, Rebuilt 4.0 @ 244,000 miles.
Apollo - 2008 Mazdaspeed3 - Mazdaspeed CAI, Mazdaspeed CBE, Prosport boost gauge.
Velvet - 2005 Ford Focus ST - Wife's ride