When I use my Jayco high-tex built in tank flusher... water comes out the side of the coach below the connection????? to mush pressure or loose connection I have a Jayco Eagle superlite
The exact thing happened to our brand new Dutchmen this year on our first trip out. While flushing the black tank using the outside flush connection, water been coming out from under the side of the TT under the black tank flush connection. I found the water commi from inside the TT, under the bathroom sink. There is a back flow valve that is either faulty or connected backwards (I still haven't had a chance to test it again). I would start there. After researching it I found that that is actually a common problem with black tank flushes.
I had a leak problem with mine as well. The connection was behind the kitchen drawers. Th fix was as simple as pulling out a drawer and hand tighten the connection. I would check all the connections.
Mine leaked too. The hose fittings were lose. I tightened with a set of pliers, and they haven't leaked since. I imagined they were only hand tight from the factory and the road vibration loosened them enough to leak.