Back flush issue

[lumpy75]

I seem to have a plugged backflush. Can not get any water to go into the tank. Have tried some things to clean the tank out but not working. Have seen some things on here about a check valve in the line. I figured the tip was plugged but if there is a check valve where would I find it?

 

[Rene T]

The first thing I would look at is to see if there is a screen at the inlet where you connect the hose. If there is one and it's clean, just behind it there may be a ball which would be a check valve. If there is one use a pencil with a eraser and see if it will push in.
The only other thing is there is a backflow preventer. In mine, It's located under the bathroom sink. It's black and it forms a 90 degree bend in the piping. 
I have heard of some people finding that the holes at the nozzle tip get plugged up. It sounds like it's rare but it does happen.  It required them to drop the belly of the RV, locate where the flushing line enters the tank and remove it for cleaning. 

 

[lumpy75]

Thanks for the info.

 

[mdbass]

I'm assuming the system worked before the current issue(s). Regardless, I thought that I would share that the last two 5vers I have purchased had their check valves installed backwards. BTW - both valves were located under the bathroom sink. Which brings up a slew of questions; especially why it was never noticed. Perhaps some people don't use the system or aren't sure what it's purpose is?

 

[lumpy75]

I did solve this issue. Did not find any kind of backflow preventer I have to assume it is mounted on top of the tank. Thanks FR no way to get to it unless you drop the tank. Turned out it had dried out and sealed shut from being unused when it was in for repair. I put regulated air to it. It lifted at about 50 lbs. Put water on it and it sealed again. Went back to air and once again 50 lbs but pushed some water in this time. After that worked perfect. Ran water for about 15 min to get a good flush on the valve.