I have a twist and lock pump assembly for a manual jabsco head. when trying to pump on dry setting, I get back pressure that makes it hard to empty the bowl. Baffling part is this will happen with no hoses connected for discharge to holding tank. This means thatt it cannot be an obstruction in any line. The wet dry valve seems to want to cheat to wet when pumping. This is the second pump assemble I have tried and this happens within two or three uses. If I physically hold the valve over it works. Anyone else have this issue. Jabsco is telling me no one has had this issue and keep telling me to return it to where I purchased it from.
Back Pressure on Jabsco
- Thread starter dave desseyn
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That's Exactly How They Design ...................
.................... the bloody things. To p*ss you off and make you use two hands to pump the head. And then fall on your face when you're under sail in rough waters.
No, I don't know of any means of stopping the lever from sliding over to "wet" position other than making sure that the lever and any contacting surface within the pump body are free of any lubricant. In that way the lever is a little more likely to "stick" in the dry position. This will improve performance about 0.5%.
However .............................. when all is said and done, I still think the Jabsco head is the best value for the money out there
. Everyone on this site just loves to beat the crap out of Jabsco heads. It's a national pastime. Having said that, I've had mine for thirteen years and it's still doing very well indeed. The maintenance was a bit of a steep learning curve in the beginning and I initially wound up stripping the screw threads on the pump body the second time I took the pump apart. But after a while and a simple modification on the rod and piston (I now have two piston rings in the pump) the head behaves perfectly.
My suggestion would be to keep the head and study the pump carefully. It is possible to live with a Jabsco head.
.................... the bloody things. To p*ss you off and make you use two hands to pump the head. And then fall on your face when you're under sail in rough waters.
No, I don't know of any means of stopping the lever from sliding over to "wet" position other than making sure that the lever and any contacting surface within the pump body are free of any lubricant. In that way the lever is a little more likely to "stick" in the dry position. This will improve performance about 0.5%.
However .............................. when all is said and done, I still think the Jabsco head is the best value for the money out there
. Everyone on this site just loves to beat the crap out of Jabsco heads. It's a national pastime. Having said that, I've had mine for thirteen years and it's still doing very well indeed. The maintenance was a bit of a steep learning curve in the beginning and I initially wound up stripping the screw threads on the pump body the second time I took the pump apart. But after a while and a simple modification on the rod and piston (I now have two piston rings in the pump) the head behaves perfectly.My suggestion would be to keep the head and study the pump carefully. It is possible to live with a Jabsco head.
I've had the problem twice now
I replaced the original (1998 vintage) Jabsco with a new one in about 2006 after having this problem. After about 5 years, that one also exhibited the problem so last month, I bought the twist and lock pump replacement and all's well again. The new pump assy was about $60 on Amazon, fixed the problem.
I took the old one apart and the rubber gasket with molded in metal inserts was warped badly, so I assume that was the cause. I don't understand why a nearly new one would have backpressure unless there is a factory defect.
i.e., back pressure on dry pumping only, wet pumping is normal.
I replaced the original (1998 vintage) Jabsco with a new one in about 2006 after having this problem. After about 5 years, that one also exhibited the problem so last month, I bought the twist and lock pump replacement and all's well again. The new pump assy was about $60 on Amazon, fixed the problem.
I took the old one apart and the rubber gasket with molded in metal inserts was warped badly, so I assume that was the cause. I don't understand why a nearly new one would have backpressure unless there is a factory defect.
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Re: I've had the problem twice now
There is a flapper valve in the upper pump assemble that is notorious for creating the issue you describe. If you are luck enough to get the top off and replace it without breaking any of the plastic screw stubs, you will have likely fixed it. A much better solution is to replace the pump assembly.
There is a flapper valve in the upper pump assemble that is notorious for creating the issue you describe. If you are luck enough to get the top off and replace it without breaking any of the plastic screw stubs, you will have likely fixed it. A much better solution is to replace the pump assembly.
Actually, the rubber for the flapper is the fault. Years ago I took one apart and rebuilt it with roof flashing (Home Depot) rubber. Use a new one as template and cut it with an box-knife. Move the bronze weight to the new one. The rubber (for the roof) is pretty tough and immune to freezing and antifreeze.
Yes, i get that OP problem once in a while. And no, you shouldn't get it. I just move the switch to wet, then back to dry and it usually works. Just don't force the pump if there is resistance. Otherwise, see #5, but there is no need to replace the whole pump
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