Jabsco toilet - strange flush resistance

[LiftyK]

Thanks all for your supporting comments. My next step is to contact Jabsco and share the combined feedback.

 

[Graham376]

In my case, all was working well with the old pump. Changing to the new pump with no change to the pipes. Furthermore, when the bowl empties it goes straight to a tank. No seacock is involved.

Similarly, the up stock to bring in seawater works ok. It is only the downstroke that resists, and only on the flush setting.

One of ours does the same but it's an old pump, maybe 10+ years. Another of those jobs I haven't quite got around to.

 

[VicS]

The flush water comes in with minimal resistance. Only the downstroke gives resistance.

OP (me) had the same symptoms as mikegunn

The downstroke pumps the waste out ( to the holding tank in your case ) and draws flushwater in to the upper pump chamber. You know there is no problem pumping the waste out therefore the problem is with drawing flush water in.

(The upstroke draws waste into the lower pump chamber and delivers the flush water from the upper chamber to the bowl)

Check the inlet strainer grill if there is one, ( they get blocked with antifouling! ) the inlet seacock and the hose from the seacock to the pump head.

It is possible that there is a problem within the top valve assembly .... maybe incorrectly assembled.

( Jabsco suggest detaching the inlet hose from the seacock ( after closing it) and trying to draw water up from a bucket. If you can draw water up from a bucket the problem lies with the inlet seacock and strainer. If you cannot the problem probably lies within the top valve assembly.

There are a number of JabscoTech videos on the manual toilet here Jabsco Manual Marine Toilet Technical Support

See, in particular # 2, which explains how the pump works , and # 6, which describes the fitting of the "top valve gasket"