I was following this previous “Strong Back Pressure in Head” thread as we happened to have the same issue just recently and are actively trying to solve it. That thread appeared to solve the original posters problem then seemed to change into a bunch of posts where other posters shared their experiences with toilet issues. My problem appears to be almost identical, but unfortunately I don’t think it is going to be as easy as replacing the pump. I hope I am wrong.
First, a quick question for Peghall, I tried to follow the instructions for your test from your post on the other Backpressure thread, but had a question. I disconnected the discharge hose from the pump (when I did this pressure was released). The flush water
inlet and all other connections were connected. At this point you said to see if it “works” in both dry and wet mode. In both dry and wet mode I could pump without backpressure. In wet mode as soon as the flush water
enters the bowl above a certain level it slowly drains out of the discharge connection on the pump because the flapper valve (not sure if that is the official name) doesn’t prevent water in the bowl from coming out. So by “see if it works” do you mean being able to pump it without back pressure? Or something else?
First our setup: We have the Jabsco
manual pump toilet that pumps directly into the top of our holding tank
through the discharge hose. From the bottom of the tank the waste goes directly into a hose that goes down to a seacock for discharge overboard
or there is a pump out deck
access. It is vented and the vent is NOT clogged. I’ve checked that and even did all of my experiments with the pumpout deck
access open just in case.
Here is what we are experiencing: We are the original owners and have never put anything into the toilet that we didn’t eat ourselves. We are strict about that. After using the head
and pumping several times the pump began to “push back”, meaning there was backpressure causing the pump handle to be increasingly difficult to pump. There was enough pressure that after forcefully pumping against the backpressure in hopes that it would push through, it actually inverted the joker valve. We then replaced the joker valve. Not surprisingly this didn’t solve the problem, but needed to be done. Next we replaced the pump with an older pump that we had replaced last year and kept around as a spare (we usually replace the pumps annually). Still experiencing backpressure after about 3-5 pumps. Next up, we used a 5 meter snake and actually snaked the full 5 meters. This head
has a long discharge hose to the tank so I’m not sure exactly how long it is. Plus it is extremely difficult to replace. We just finished snaking it and are still getting back pressure. Nothing so far has worked.
What is is definitely NOT: Please don’t post saying you fixed your problem with any of these issues, as I have checked and double checked these and it is not the cause of our problems: all seacocks are open, the wet/dry valve is being pushed all the way to one side or the other, the vent is not blocked, I repeat, the vent is not blocked, any suggestions to “put X or Y into the toilet and pump it through” is not helpful because I cannot pump anything through because of the backpressure.
We’re stumped. We are hoping that despite everything pointing to a blockage in the hose, it is something else that is easier to fix. The only thing we can think of is that maybe the hose is just longer than 5 meters and the snake pushed the blockage close to the top of the tank, but not fully through. Really at a loss here. Any ideas?