What is this on top of the tank?

[srisitt]

What is this with the blue cap to the left of the fuel pump? I can't find any info about it in my manual. I thought it was a filter.

 

[snoranger]

Roll over valve, fuel vapor vent, check valve... Everyone calls it something different. It's the vent for the fuel vapor. It's got a check valve built in to stop fuel from leaking if you ever roll over.