2013 Montana 3900 FB sewer problems

[cozycamp]

We've owned this unit for a month & half.Been having sewer drain problems with our 2013 montana 3900fb. it has two bathrooms. When dumping paper gets caught in valves. We don't empty until it is over 2/3 full & rinse for five minutes before closing valve. I'm thinking the valves are set in horizontally not vertical so it's hard to flush the paper out completely. Anyone have any ideas? Thanks in advance.

[dieselguy]

What are you using for TP?? It should be well dissolved by the time you dump. Use lotsa water when flushing the stool as well.

[WeBeFulltime]

Did you buy it new and if not do you know how the previous owner treated it?

[stengels]

Agree with dieselguy. We have the same unit, have had it for 3 years now, and have not experienced the problem. If problem persists, you may want to get an external flush product to see if this helps. By the way, our black tank flush doesn't hardly work on the half bath toilet. When I run the black tank flush, I close everything up, let the front black tank fill, and also run about 5 minutes of water into this lower tank, and then empty again.

[1retired06]

Our 2015 3910FB had the wrong cable flush valves installed and even they were installed incorrectly.. Thanks to Keystone. Dealer replaced under warrenty.

[DQDick]

Could be any of the above, but if your using regular toilet paper and not the fast dissolving stuff that's your real problem. Using lots of water is also a good idea.

[jcurtis934]

For me, only rinsing for five minutes would be a huge problem due to the outlets setting higher than the bottom of the tanks, horizontal pipe runs. Have a clear section right at the campsite sewer inlet and can see everything flowing by. Tp is broken down fine, but other stuff isn't always. My system of dumping and rinsing takes about 20-30 minutes...but it flows crystal by then...even if I fill toilet bowl with water and dump that in as a check. John

[cozycamp]

Thanks for all of the good advise. We do use nothing but rv qucik dissolving TP. We bought it used & the half bath valve was sticking then. The dealer replaced it under warranty but now is sticking again plus the other black tank is now sticking. Seems like a poor design to me. May call Keysone to see if they will do anything about it. I'm going to try all of the suggestions & see what happens. Thanks again.

[1retired06]

On our 3910FB, I replaced all four cable flush valves with threaded rod direct pulls because we got tired of the same problem you are describing.