We have a Flojet hardwired and have used it a dozen times without a problem. Today it couldn't pump out and I heard gurgling in the RV drain pipe. After several tries, I reversed polarity and it was back to normal pumping like before. Can a DC pump reverse direction for any reason besides polarity. Just to be clear, I did not have the polarity reversed as it has been hard wired and always worked properly before today
if you reverse polarity it will operate in reverse. It's possible if you did it once (by accident) it sinks that direction, but that's just a guess. I have mine on a Anderson plug so there is no way i can accidentally hook it up in reverse. I've use my Flow Jet over a couple dozen times and never had it go in reverse on me..