macsrator pump fuse blowing

[kylewilliams]

hello, I purchased an ericson 27 with a built in head, holding tank plumbed to an on- deck pump-out fitting (for a dockside sucking pump-out) and a mascerator pump for pumping out through a thru hull. The previous owner had never used any of it. (I guess he just held it for a long time???).

the head and dockside pump-out have been working great, I never bothered with the mascerator until now. it is a Jabsco self priming 18590 12v 16 amp pump (probably very old. I have no idea). was plumbed but not hooked up to the batteries. I wired it per the manual with a 20 amp fuse and switch, 10 guage wire ran about 15 feet. I sailed offshore many miles and flipped the switch. it ran great, pumped out the tank in no time, and then blew the fuse. next time it was full, I put in a new fuse, same thing. drained the tank, then blew the fuse.

I guess I could do nothing and just plan on burning a fuse every time i use it, but I am sure somthing is amiss and i would hate to ruin the pump (if it isnt already..) or burn up my boat.

any siggestions for what can cause this? I assume the pump could be faulty, but it seems to pump great. The hose that it pumps out to does have a bit of a kink in it as it courses to the thru-hull, but it does not seem to pinch off the flow that much. I will try to rectify that kink to eliminate it as a possible problem.

the outlet hose (the one with the kink) is smooth plastic tube 1 1/4 " OD that reduces to a 1" OD fitting that goes to the thru-hull. Could this size reduction be causing the the pump to strain itself to the point of blowing the fuse? (I hope not. Increasing the size of the thruhull would not be an easy option..)

any help would be much appreciated
cheers
kyle

 

[Peggie Hall HeadMistress]

Hmmmm....Check your tank vent for a blockage

Are you certain that the macerator and/or the pumpout are actually emptying the tank? Not just pulling enough out to let you think it's getting all of it? 'Cuz that sounds like what happens when the tank vent is blocked, causing the macerator--or the pumpout--to pull a vacuum...when nothing is going through it, that would cause it to blow a fuse or a breaker. Big clue: your tank seems fill up awfully fast. That COULD be because it's never anywhere near empty...that only a few gallons get pulled out of it.

All hose sizes use the ID...all fittings use the OD. So a hose that has a 1.25 OD is most likely a 1" hose--which is the size of the discharge fitting on the macerator and the correct size to fit onto a 1" OD thru-hull fitting. So I don't think there's any reducer in it. A kink in that hose could definitely cause a problem!

You describe it as a "smooth plastic tube"...is it any different from the rest of the sanitation hose? It should be the same type of hose. If a PO used a water hose, that's bad...and prob'ly the reason it's kinked.

If none of the above is the answer, call Jabsco: 978.281.0440

 

[Steve Dion]

I wonder if you have the correct sized wire/fuse?

http://www.pumpagents.com/pdf/JabscoPumps/18590-0000.pdf

 

[Peggie Hall HeadMistress]

Weeelll...

...in the very instructions you posted, he does.

 

[kylewilliams]

Re: Hmmmm....Check your tank vent for a blockage

thanks for the replies.
peggy: the head is the type where the throne sits directly over the tank (sort of like a fancy portapotty) and by opening the flapper ball i can see the in the the tank and confirm that it is empty (at least other than what would be left below the dip tube) . The vent seems open and clear, when I use the shore pump-out I can confirm that air is entering the vent and it empries nicely.
the tube that is plumbed out of the tank and up the pmp and then on out to the deck fitting is a very heavy 1 1/2" grey reinforced accordian sort of tube. (not that cheap white plastic stuff..). the tube running from the pump is a 1" heavy clear plastic non-accordion tube, that does indeed allow it to kink. I will remedy the kink.

Steve, the wire is a 10 gauge standed wire, as specifieded in the sheet you referenced, with 20 amp fuse link and switch.

thanks

 

[Peggie Hall HeadMistress]

Weeelll...

According the spec in the very instructions you posted, he does (what is "pumpagents.com"???)...However, the current instructions on the mfr's site http://www.ittflowcontrol.com//files/18590_series_sealed_macerator.pdf call for #14 wire.

He says the macerator is old, so we can't know which is right for THAT macerator...whether a redesign since it was made calls for a bigger wire or not. So he really needs to call Jabsco.

 

[kylewilliams]

hello again, upon further exploration and talking to Jabsco, I removed the mascerator pumo and it is toast. Siezed up (thus the blown fuses...). Obviously I could just replace it but I am interested in exploring a manual pump-out system. (I am a big fan of anything manual whenever possible. seems like much less can go wrong, although slightly less comvenient from time to time...) Remember this is for pumping from the holding tank. I happen to already have a spare Whale diaphram pump with 1" ports. Is there any reason I could not just plumb this in and pump out the tank as needed with this? In the Whale website they seem to indicate that pumps like this can handle "slurry" which seems to be what is in the holding tank. Do I really need the "mascerator" if I am willing to pump by hand? any thoughts on this would be appreciated.
cheers
kyle

 

[Peggie Hall HeadMistress]

Whale manual pump is good choice for tank discharge

But it needs to be a model designed for that purpose, and if yours has 1" ports, I don't think it is..'cuz their toilet pumps have 1.5" ports. Check out the Whale Gusher...compare it with yours.

 

[Steve Dion]

Kyle:

Did you try using the screw on top of the pump. Ours has locked up a few times and we just turn that screw to loosen it up?

 

[Head Master18695]

To follow up a bit on what Steve Dion had to say, Jacbso-type macerator pumps use an interference-fit rubber impeller inside, that is turned by the motor to generate suction. If the pump hasn't been used in a fair amount of time (more than a month or so), it's best to remove the pump from the hoses, disassemble it, and lubricate the impeller and the inside of the pump cavity BEFORE trying to use it. When the pump sits unused for extended periods of time, the rubber impeller has a tendency to adhere to the inside of the pump housing, becoming "stuck." Then when you try to run it, the impeller is stuck to the inside of the housing, which causes an overload on the motor, blowing the fuse. If this happens a few times, you'll likely burn out the motor.

As was mentioned earlier, on a lot of the Jabsco-type macerator pumps, at the other end of the motor, the shaft sticks out and has a screwdriver slot in the end of the shaft. This is intended to allow you to use a screwdriver and turn the motor shaft manually, to "break the impeller loose" inside the pump. Sometimes the end of the motor shaft has a coverplate over it, that must be first removed before the end of the shaft is exposed. So after removing the plate, use a screwdriver and turn the motor shaft at least half a turn before applying any power to the pump motor.

But again, if the pump has sat unused for an extended period of time, don't even think about simply applying power to it and expecting it to run - it most likely won't.

 

[kylewilliams]

Re: Whale manual pump is good choice for tank discharge

so sorry, my mistake, it is a Bosworth Guzzler. Delrin body, the diaphragm is 4" across. The Bosworth website says the pump is for bilge, fluid transfer and santiation applications. With the proper size hose adapters, would it be a mistake to use a pump like this for pumping out the tank?
thanks

 

[Peggie Hall HeadMistress]

Use it...

You already have it...Bosworth says it can be used for sanitation...use it! It's not an irrevocable decision, ya know!:dance:

 

[Bill Roosa]

"Sanitation" can have two meanings, pumping flush water and pumpin sewage. I'm positive it will handle flush water. Poo on the other hand is pretty hard to keep from sticking to the valves and can result in valves not closing (avoid corn). If it has springs that close the valves then you should be OK.

 

[Bill Roosa]

While mucking around in my boat I noticed the following odd behavior of my macerator pump. The pump would stall (first use in a long time) but would not draw very much current. After manually turning the impeller and freeing it up the current draw was directly proportional to the motor speed. The faster it ran the more amps it sucked up. This is exactly backwards from how I was taught electric motors worked and none of my other motors work this way. I inquired of my dad who wound electric motors for 40 years as a profession and he said it was a feature of (you guessed it) how they are wound. Apparently some safety regs require that certain motors be certified to not catch fire if their shaft is prevented from rotating and voltage is applied to the windings for an HOUR. Macerators are one of the motors.
SOOOOOO
If she pumps fine and then blows a fuse after the pumping is done does the motor turn faster at the time the fuse blows? This implies that the motor is fine and you just need to hit the switch faster once the tank empties.
FWIW

 

[jibes138]

I have a jabsco macerator and also blow a 20 amp breaker when I use it. It will run for a period of time, runs fine and pumps great then suddenly blows a fuse. I rewired it to a large gauge wire to reduce losses, eliminated the in circuit switch to avoid another point of loss so I am positive I don't have a voltage reduction enough to cause a problem. I spoke to a maintenance guy who suggested the breaker might not be large enough. He said a 20 amp breaker has some margin for safety and will likely break at maybe 18 amps. The macerator specification is 16 amps or so. I'm thinking if the motor is drawing a little more and the breaker is weak it may need a 25 amp breaker instead. What is the risk of this? I haven't noticed any overheating or other issue. I can replace the breaker easy enough with a new 20 and see what happens.

 

[Steve Dion]

Jibes:

If you pump has the screw on the top, try turning the pump by hand.

Our pump does the exact same thing when not used for a while. Turning the pump manually once or twice usually resolves the problem.

 

[Peggie Hall HeadMistress]

Bill...how often do you use the macerator vs. using a pumpout?

 

[jibes138]

Breaker tripping

Steve,
My problem is the macerator runs fine, pumps beautifully, and then suddenly the breaker trips. I reset the breaker and it pumps fine again and after a bit it trips again. So it isn't an initial surge that is causing the overcurrent, it is while it is pumping after maybe 2 gallons or so. Why would the load on the motor suddenly increase enough to trip a breaker? This seems from the thread to be a pretty common problem. Just wondering if a 25 amp breaker would solve the problem?

 

[jibes138]

Maybe Peggie's note on the vent tube not breathing enough is a clue. If the tank can't fill with air fast enough the delta p will try to crush the tank and the macerator loading will increase. Then as I reset the breaker it fills back up allowing the pump to work ok until it fails again. Looks like another chore upside down in a confined space to get at the vent hose. Very well could be the problem, certainly makes sense.

 

[windyjazz]

Like many here I have experienced the same problem. My theory is that pump failure is not too far off. I do the same as other have suggested rotate the pump manually with screw driver or quarter and hope the fuse doesn't blow. I'll bet you can turn a brand new pump with your finger. A new macerator pump is moving up on my personal list of replacing.