Cutout a 12"x12" flap in the Coroplast liner directly under where you think the black tank valve is located.
Don't bother to try and peel the liner back, not worth the trouble.
You should be able to see any problem with the handle assembly, if the handle is still attached to the valve body (and is moving in and out) it might be broken inside the valve itself. Only recourse then is to replace the valve.
Like others have said it could also be blocked within the tank...and don't worry about that 12"x12" flap just use some duct tape to seal it back up.
Thanks for all the replys. Monday i will look for a back flush valve, hopefully the gate will open and try to dislodge blockage. If all fails then its to the rv shop. hate to move though, but i need the system. Lots of good Ideas though. Thanks to all.... Roy
Try putting a garden hose up the drain with the valve open. Have a 5 gallon pail ready and put it under drain. Turn the water on to the hose and push it in and out. Have someone there to close the valve once the blockage is moved. Reattach the drain hose and dump.
If the valve is stuck closed you will get fairly clean water right away. If it is clogged you will get other stuff. Catch it in the pail. The faster you close the valve the better off you will be. There will be some splashing going on, but if your careful it won't be bad. Plastic on the ground and gloves. Put a back-flow preventer on the water spicket.
I have done this and it worked. Someone in our party used to much paper. They weren't used to camping toilets. Hey it happens. I would try this before you cut into your belly pans.
bob and deb
diesel the black lab
2003 30' cedar creek rlbs 5'er
2003 ford f350 crew cab 4x4 6.0 LB
cedar creek club member
Dean, Thanks, last year in Texas the front gray water pull unscrewed and fell out. It took quit awhile to find a replacement. I screwed it in and used locktite to keep it together. i thought of that and tried to screw the black water one in but it doesn't seem to be loose. It does turn in like it is together and as before it turns like forever. I am going to cut the 12x12 opening to check things out. My kids used to call me "duck tape man" so I can us it when needed. This is just bad timing for such a thing to happen. We are in the forest and the nearest paved road is 6 miles. It's always fun and challenging to travel around this country. I'm glad that I belong to Good Sams also and have this forum to look to. As you can see I haven't used the forum much. We have been a Good Sam member since 1980 off and on. Again, Thanks to All who have respended. Roy
I have an 06 Cougar. Once the handle came unthreaded from the gate, but didn't fall out. I pushed the handle back in, and then rotated it clockwise until it rethreaded back into the gate. Now I routinely turn the handles to make sure they are tight. One tip though, you won't feel any resistance when they get tight. I don't know why.
Dean and Tracy Bachellier
2017 Montana High Country 293RK
HiJacker 16K double pivot slider
2011 RAM 3500 SRW Crew Cab 4X4 CTD
"It's five o'clock somewhere...."
Well, here it is.... after going through all of the suggested thoughts. I decided to hook up and go for a ride in hopes to break up the clog... This was my last venture as you can imagine for it requires, putting everything down inside, running all slides in, raising all levelers(manual), hooking up 5th wheel to truck, unhooking electric, water and sewage connections, Ta DA, Now I'm ready for a rough ride... Did it, came back, rehooked sewage, and, fuess what, pulled the black water pull and IT DRAINED.. I have learnt that if all other processes don't equate. Hook it up and rock it loose..... It was clogged up. Now I have rinsed it out thoughly and my black water gauge even reads EMPTY. It was a real pain to unhook and rehook, but it works..... Thanks to all
Roy and Sharon
Ocala National Forest, Big Scrub, Florida Camp Host 2012
We had a similar problem only reversed. Black stuck part way open. Didnt know until I went to drain some gray in a bucket and lets just say it wasnt really gray. We went to campground dump station and move fast to get the hose on. then put a hose on the flusher port and moved the valve handle in and out for an hour. It finally sealed back up. We were lucky knowone else was at the dump station. Not alot of fun. Cutting a hole in the underbelly can be some guess work if you dont know exactly where the valve is located. GOOD LUCK and let us know how it turns out.
I had the same problem recently. The rod that goes into the slide gate pulled out of the gate, but the rod did not come all the way out. I could push it back into its position, but when I would pull on it, it would pull out again. Had to replace the complete slide gate valve. Have a bucket ready.