Aqrlan my Yamaha will discharge water from the pee hole pretty much instantly when started on the muffs. Make sure you have the water hose turned on all the way. Also make sure the water intakes are cover completly by the muffs.
When I run mine with muffs, I have a bungee cord attached to ensure a tight fit. I also hold each "intake hole cover" with my hands whne I first turn on the motor to get it going...............usually see water in under 5 seconds..
My 25 hp 2 stroke Yamaha (2 cyl.) takes forever to run out the tell tale on the muffs. It starts immediately if in a tank. I seldom use muffs for this reason.