I don't remember when OEM engine mfgrs. started using "Tell Tale" ports to give the operator an indication of water pressure availability. Some recent large engines have the port directly at the rear of the engines but most, for decades, were located on the right (Starboard...curb side if you will if sitting on the trailer) side of the lower engine cowling toward the rear.....so the operator, with the helm on the same Starboard side could look back and see it. Some engines just had a hole and some had an adapter. If it's there, you ought to be able to see it.
You could pop the cowling top cover(s) and just look down at the lower cowling, on the inside, and see if you see a hose connected to it.
