Hi, I have a 1996 Regal Rush XP120 jet boat. There should be a hose that connects from the engine to a fitting at the base of the engine which goes through the hull. When the engine is running water is sucked up and passed through the cooling passages of the engine. To start boat on dry land it was suggested to me to have everything ready - hose disconnected from thru hull connector and reconnected to a garden hose - which is OFF. There is a special connector that goes on the hose fitting and the other end connects to a garden hose, at least on my engine!
You then start the engine then quickly turn on the water to the garden hose - NOT FULL OPEN - just enough to have a small stream coming out of the rudder nozzle. If water flow is too high it might cause big problems!!! You might want to install an on off valve to the end of the garden hose then adjust the flow at the spigot BEFORE you attach to engine hose.Then all you have to do is open the on off valve after you start the engine. Another thing to consider is making a 3-4 ft section of garden hose with male and female ends. Then attach the on off valve to the appropriate end.
I included an URL link to a video I made when I had a problem with my engine starting. Be sure to reconnect your engine hose to the thru hull connector at the base of the engine BEFORE putting into the water.
If you have any questions please let me know.
Good luck,
Ski
https://m.youtube.com/watch?v=KlTth_VFPX4