I have had a scraping sound too, but I believe it is the fuel lift pump surging fuel back into the tank. I noticed it was louder as I had less gas, it also increased in frequency as the engine RPMs increased.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth