[DutchmenSport]

I have the same issue with my 375FL. I found out the bottle holding the antifreeze has to be level or highter than where the hose attaches to the inlet. If you raise the jug, it will probably begin to suck it up. If it's lower than the fill connection, it won't. I set my jug of pink-stuff on a step ladder beside the trailer. It works great then, as long as it's as high or higher than the hose connection.