I sent you a PM. Leave the nipple end screwed in and quick connect on the hose. This way when you turn onm the water it won't allow water to fill the engine till it is connected. I install a on off valve so I can connect to my engines at once then start them up and open the valve after they are running. Shut off the water after 15 seconds of flushing and then the engines. All from inside the boat with the water shut off valve close at hand and the lanyard close too.
Karl