OPTIMAX VSP Cross-over tube

[captdale]

So - 2010 , 200 hp, DFI. The cross-over rubber tube on the bottom of the optimax VSP that runs between the moisture sense bowl and main fuel bowl. Needle valve on both ends. What exactly is the purpose of this tube. I suspect it is a convenient way to drain either or both bowls. Can't think of any other use. Any thoughts on that ??? CD