Injectors work by creating a pressure difference between the input and the output. With a bigger orifice that the 8 gpm injectors use, it makes it very hard to get a good draw or if it will work at all. The hose alone creates back pressure which keeps the injector from drawing adequate soap. I use a 3-5 gpm injector on my 10 gpm machine just so I can get good soap with a long hose run.