is this a filter??

Just a guess, but that looks more like some sort of one-way check valve to me. Something to do with evaporative emissions control maybe?

I'm thinking the same thing. Factory style crimp clamps. Willing to bet it's on a vent line for tank. Probably a mini seperorator so fuel does not travel down line in case of tank overfilling or fast cornering with tank full. Check the evaporative section of Manual to see if it's there.