Black tank flush plugged

[macminn18]

Seems the black tank flush is plugged in our 2011 Ultralight Passport. I hook up the water and it doesn't flow into the tank. Is the assembly somewhat accessible?

[JRTJH]

Did it work last year? If so, then if you removed the anti-siphon valve for the winter, did you reinstall it "backwards" ???

If not, then it's probably some "dried gunk" on the end of the spray nozzle inside the black tank. You may be able to loosen anything that's dried to the nozzle by filling your black tank, adding some "digester" chemicals and letting it sit for a few days.

If you do need to access it, you'll probably need to remove the coroplast underliner beneath your trailer to get to it. While it's not impossible to do, it is time consuming and you'll be working "on your back under the trailer to pull the screws, rivets or power driven nails to drop the coroplast. Pay attention to how it comes off so you can reinstall it the same way !!!!!

I'd first check that anti-siphon valve to be sure it's installed properly and is working.

[Bisjoe]

When I used mine yesterday I was surprised at how long it took for the water to start flowing out. With the small holes it comes out with force but much less volume than what you get from a hose, and they can get clogged up. I got this shot from a Youtube video.

https://www.youtube.com/watch?v=-YPkEcyhf3k

[simpson3701]

newer models have back flow preventers (check valves) in the supply line prior to entering the tank itself. They are normally installed on the same side of the trailer where your flush hose fitting is. They are also located in a cabinet or under a sink in the living space of the trailer. Once found, you will see an in-feed line into the device and a discharge line from the device. I took mine out and replaced with a 90 degree 1/2" brass fitting. Theses check valves are famous for trouble.

[DOWva]

I went to the video and watched how to repair the black tank flush valve wow it seems pretty straight forward and easy.

[notanlines]

Mac, don't get the cart before the horse. First, before you start making plans of a major repair job, take the advice given so far. Be POSITIVE that your anti-siphon valve is fully operational, and that there is water pressure at the valve. It is doubtful that all the holes in the flush system would be plugged up.

[ChuckS]

If you are lucky like we are the sewer drop. Line is a straight level shot into our black tank. I use an external Valtera clean out connection with clear tube and gate valve. I can see when the black tank is clean. Never used the black tank built in flush connection nor do I intend to

[flybouy]

After watching that video I have one piece of advice, Always, ALWAYS use a table cover on public picnic tables! SHUDDER, SHUDDER, GAG.

[slow]

After a couple of years, our black tank flush was plugged. Turned out to be kink in the pex. It probably started as a bend and over the years it kinked. A 90 degree elbow solved the issue.

[PhilC]

Hoping this is the correct place to post this.. I Just purchased a brand new 2018 Passport 2670bh and when connecting the hose to the black tank flush inlet and turning on the hose nothing happens. Seems like it is plugged OR there is a valve somewhere that I have to open? If so, any ideas where it might be or look like? Any feedback would be greatly appreciated.

[chuckster57]

Welcome to the forum
Most likely the anti siphon valve is backwards. Common place is under the bathroom sink, or behind the shower faucet knobs. Some members have replaced it with a brass one, I still have the factory one.

When you find it, there will be an arrow on it indicating direction of flow.