Grill no 2 in yr pic is an outlet so that ain't the problem. The no 1 inputs on both sides are where the water is drawn in.
If your motor is a Vmax, I have seen pics where the Vmax has two sets of water inlets, the ones (1's) in your photo and also two more at the front of the bullet ( gear case) like the current 4.2lt four stroke yammies. If that's the case these front inlets are connected so the water in (1) will just fall out the front ones. You either need a barrel to immerse the leg in and cover both sets of inputs or use the hose attachment. My F225F ( 4.2lt) user manual only recommends hose attachment flushing and never earmuffs because of this.
If you don't have theses bullet inlets you have another issue.
Cheers