Do you know you have it for sure? It should be labeled "black tank flush" You only have to hook up a garden hose to this and turn it on. They recommend in the manual to leave the black tank valve open, but after draining mine I'll fill and flush my tank several times to get all the corn out. Whatever you do don't hook it up with you black tank drain valve closed and go off and do something else, you'll end up with a bigger mess than you want.
I've always used mine (excuse the pun) and never really seem to get all the crap out.
Our flush kit hose connection is down low in the skirting. Ithas a small hose running thru the frame into the underbelly which by-the-way, the hole in the frame should be sealed because mice got in thru it and made a mess. Use expansion foam or duct tape.
Probably the best way to know if it is working is to do it with an empty black tank. Once the tank is empty turn it on and see if there is any water coming out of the drain hose. There was an issue with ours that was fixed under warranty. The tech told me the sprayer was installed in the wrong place. Both (we half a 1/2 bath with its own black tank) are now working as advertised.
Art and Karen
2013 Itasca Sunstar 35F, 2013 Ford C Max toad.
170 nights in 2013
132 in 2014