Jabsco back pressure

Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
@Peggie Hall HeadMistress

Just installed a new jabsco big bowl toilet last year .( I know should have got a Raritan but they were on good sale price ). When I pump with water there is no issue but when I flip to dry there is back pressure on the pump handle. Also get air pressure back through he joker when stopped pumping . Removing the waste cap does not change anything.

Tried spraying water down the vent but no change. Could it be the vent plugged or something else plugged .
 
May 12, 2004
1,502
Hunter Cherubini 30 New Port Richey
When I pump with water there is no issue but when I flip to dry there is back pressure on the pump handle.
Jabscos are on the charter boats that I captain. Damn things! Anyway, if the lever is not ALL the way over to dry it will not pump. Just a mm does it. Hold the lever over hard and pump once. That gets it going.
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
Yep
Jabscos are on the charter boats that I captain. Damn things! Anyway, if the lever is not ALL the way over to dry it will not pump. Just a mm does it. Hold the lever over hard and pump once. That gets it going.
Yep have tried that. Had that issue with previous Jabsco .
 
Dec 2, 1997
8,709
- - LIttle Rock
Roland's on the right track...it appears you have a problem that's very common in Jabsco manual toilets--a failed wet/dry cam. The wet/dry "valve" is actually just a little "gate" (the cam) that the lever swings to block or unblock the flow of incoming flush water. Due to either a tooling or mfr'g flaw, it hangs up...creating back pressure that feels like pumping against a clog or blocked tank vent, except it only happens in one mode--usually the dry mode. Jiggling the lever can free it up while you're flushing, but it's not a cure. The real cure: replace the wet/dry cam assembly. Jabsco often sends out a new one for no charge--and yours is new enough that they might...but then you have to take the pump apart to replace it, which can be a PITA and really messy because you can't flush water through the pump to clean it out before you take it apart. So you might just want to struggle with it through the rest of this season and replace it with a PH SuperFlush "conversion" (everything but the bowl, seat a lid) next spring. The mounting bolt pattern is designed to match your Jabsco. Raritan PH SuperFlush

--Peggie
 
Sep 2, 2011
1,041
Hunter 27 Cherubini Alum Creek State Park
Had the same problem with my Jabsco a couple of years ago so, I replace the whole pump assembly. The new one did the same thing. Happy to hear it's a mfg defect and not a problem with the venting I installed last year (new 1" lines).
I would do the Raritan everything-but-the-bowl replacement, but on my H27 the new compression post I installed would interfere with the Raritan handle.
Bummer!
image.jpeg
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
Roland's on the right track...it appears you have a problem that's very common in Jabsco manual toilets--a failed wet/dry cam. The wet/dry "valve" is actually just a little "gate" (the cam) that the lever swings to block or unblock the flow of incoming flush water. Due to either a tooling or mfr'g flaw, it hangs up...creating back pressure that feels like pumping against a clog or blocked tank vent, except it only happens in one mode--usually the dry mode. Jiggling the lever can free it up while you're flushing, but it's not a cure. The real cure: replace the wet/dry cam assembly. Jabsco often sends out a new one for no charge--and yours is new enough that they might...but then you have to take the pump apart to replace it, which can be a PITA and really messy because you can't flush water through the pump to clean it out before you take it apart. So you might just want to struggle with it through the rest of this season and replace it with a PH SuperFlush "conversion" (everything but the bowl, seat a lid) next spring. The mounting bolt pattern is designed to match your Jabsco. Raritan PH SuperFlush

--Peggie

Ok thanks. Didn't want to start tearing stuff apart that wasn't going to solve the problem .may just have to look into the raritan once and for all.
 
Sep 2, 2011
1,041
Hunter 27 Cherubini Alum Creek State Park
Roland's on the right track...it appears you have a problem that's very common in Jabsco manual toilets--a failed wet/dry cam. The wet/dry "valve" is actually just a little "gate" (the cam) that the lever swings to block or unblock the flow of incoming flush water. Due to either a tooling or mfr'g flaw, it hangs up...creating back pressure that feels like pumping against a clog or blocked tank vent, except it only happens in one mode--usually the dry mode. Jiggling the lever can free it up while you're flushing, but it's not a cure. The real cure: replace the wet/dry cam assembly. Jabsco often sends out a new one for no charge--and yours is new enough that they might...but then you have to take the pump apart to replace it, which can be a PITA and really messy because you can't flush water through the pump to clean it out before you take it apart. So you might just want to struggle with it through the rest of this season and replace it with a PH SuperFlush "conversion" (everything but the bowl, seat a lid) next spring. The mounting bolt pattern is designed to match your Jabsco. Raritan PH SuperFlush

--Peggie
Actually, after looking at the tech drawing in the link you provided, I see the flush handle doesn't stick out any farther than the front of the bowl. In all the marketing pics it sure looks like a longer lever. Maybe I'll check into it. Hmmmm....
 
Dec 2, 1997
8,709
- - LIttle Rock
Actually, after looking at the tech drawing in the link you provided, I see the flush handle doesn't stick out any farther than the front of the bowl. In all the marketing pics it sure looks like a longer lever.
It has a telescoping handle, to keep it out of the way when necessary. You must have missed that in the promo sheet I sent you.
--Peggie
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Jabscos are on the charter boats that I captain. Damn things! Anyway, if the lever is not ALL the way over to dry it will not pump. Just a mm does it. Hold the lever over hard and pump once. That gets it going.
+1 to Roland. As part of a pre-cruise checkout, I tell crew just put your finger on the lever to push away from bowl while you do the downstroke and it will keep working.
 
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