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Old 14-10-2013, 10:27   #31
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Re: Macerator Acting Strangely

I don't have any way to check the amps at the pump, but it is wired on a 15' run of new, unspliced, #10AWG wire. It is connected to two type 24 batteries showing 13.5V and it behaved the same with and without the motor running when the boat was in the water. I think I've pretty much eliminated any problem with getting good power to the pump.

Also, now that the pump is running again, I'm connected to exactly the same setup and it is working fine.

I noted in the Jabsco instructions that this motor has a 'fifteen minute duty cycle'. Does that mean it can be run for 15 minutes safely and then should be shut off, or does it have some kind of sensor and shuts itself off? I've never run it anywhere close to 15 minutes as my tank is only 20 gallons, but if there is an internal senor, perhaps it could be bad.

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Old 14-10-2013, 20:42   #32
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Re: Macerator Acting Strangely

"does it have some kind of sensor and shuts itself off?"

Interesting thought. The following is from the description of the motor used on the Jabsco macerator pump.

"Includes Run-Dry Protection Device
that shuts-off pump."

If there is some kind of sensor it must be built into the motor as it doesn't show on the parts list. Why don't you contact Jabsco and ask them?
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Old 14-10-2013, 20:53   #33
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Re: Macerator Acting Strangely

WADR, RTFM. It should say these pumps do NOT like to be run dry and that the switch should be close to the pump so you can turn it off immediately when it has finished emptying the holding tank. I know this because I just bought a new one to replace my 26 year old OEM (going Shurflo instead of Jabsco). Good luck.
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Old 16-10-2013, 12:07   #34
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Re: Macerator Acting Strangely

Hopcar: I took your advice and fired of a question to Jabsco (Xylem). Surprisingly, Jeff Lander, a product specialist got back to me very quickly and provided two pieces of information.

First, regarding the 15 minutes of operation and the reset switch:

It means that the pump can be run for 15 minutes safely and then should be shut-off. There is however, a poly-switch that will shut the pump off if you run it dry for a period of time or if the motor/impeller isn’t spinning freely. If there is a blockage or if the impeller is in a set position then what happens is the motor cannot spin freely. This causes the macerator to draw a large amount of current, which trips the polyswitch that turns the pump off to protect it.

This does not quite fit my problem as my pump never shuts off, it just slows to a crawl, but it is good to know.

He also responded:

From time to time the impeller can develop a “set” position. While sitting in the housing, a few of the vanes are always bent over. If the impeller isn’t in great shape or if the impeller sits for a period of time, then what can happen is that the impeller develops a “set.” The impeller “set” can sometimes causes a breaker to trip or in some instances, cause the motor to appear to run slowly (because the shaft isn’t spinning freely). Once the set is “broken” and the shaft can spin freely again, it appears as if the speed of the motor “picks-up.” If you think the macerator is running “slowly” then pop the cap off at the back of the macerator, insert a slotted screw driver and turn the shaft to aid in breaking that set position.

Again, this does not match my situation as I've had the behavior start while I was using the motor - no time for the impeller to take a set.

I guess I'm never going to know exactly what has been going on. I have removed the holding tank and all the plumbing. Before spring it will all be reinstalled with the motor right on top of the tank, in full view and with access to the screwdriver slot in the back of the motor. It will get annual lubrication, the lift height will be decreased and the potential from a deck plumbing vacuum leak eliminated. It may yet fail agian, but I will know exactly what is NOT causing the problem.

Thanks to all the members in this list for your help.

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