marine toilet malfunction

[CRF]

I did search and didn't find exact question so here it goes: we have a 2005 270 with a jabasco pump head.
Lately it flushes briefly while pumping, but then liquid comes back into the bowel. I thought it needed a joker valve, but jabasco customer service says my line is clogged (doubful as we never put much in there) OR he thought one of our air vents was clogged. I can find the one from the holding tank to the side of the boat. He says there's another one at a high point on the waste line from the toilet.
Any helpful advise?? thanks

[Babyboomer]

I only know of one vent on a 270 my bet is the joker valve

[Dream 'Inn]

Yeah, I'm betting on the joker valve too.  Quite easy to change out, it is right at the toilet where the hose exits to the holding tank.

[merwin10]

Hi -

Yep the guy is right! If your vent is plugged you will build up pressure in the tank as water displaces the air, if the air builds up enough it will back wash! However that is what the joker valve is suppose to stop to a point!

My bet is that it is a little of both! As joker valves do wear out! As for a vent tube it may be incorporated in the suck out tube! Some designs leave a small hole in the cap to vent air versus being sealed water tight!

Pull the cap off run the water and see if it back washes! If it still back washes it is the joker valve!

Mike -

[CRF]

thanks for reply's. On the way home from work I stopped by the marina and removed the pump out cap. That should take care of any clogged vents. Anyway I still had the problem with the toilet, so I guess its a line clog or the joker valve. I had already bought a rebuild kit at West Marine so I will deal with that on the weekend.
thanks for your help !

[merwin10]

Hope you bought some disposable gloves as this is a real messy job!

Mike -