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Old 08-21-2021, 04:30 AM   #1
Join Date: Oct 2019
Location: Dewitt, Mi
Posts: 44
Dometic Vacuflush

Help needed!!!!

We have this rig for less than a year. We bought it used and there are missing documentation like the Vacuflush. Anyway, the DW flush the toilet after use, and she noticed that the Light in the VacuFlush switch was not changing to green the pump keep running. I checked the Vacuflush pump (SW series) and the bellows looked ok, there were no leak or tear on the bellow. To get matter worse, DW needed to pee and I said maybe you can still use the toilet (pee is just water), which she did. When she flush water does not go down. This is our first rig a 2014 Fleetwood Excursion. Were are camped at TT in St Clairs MI. We have a week more to go before headed home. So my questions are:
1. With the vacuflush system if the pump is not functioning do the waste from the toilet does not go down?
2. What would cause the vacupump not to stop running? After I leaned up the blellow and reassemble, I covered the exhaust of the pump with my palm and operated the pump, it seemed to created vacuum. I run it for a minute and still would not stop). When the vacupump is running and I activate the pressure sw on the tank, pump quits. So I think that the pump is not creating enough vacuum.

3. Is it time to replace the vacupump or there are still replaceable parts, I can try? What are they and wre they are located.
4. I there a way to drain the toilet?

2014 Fleetwood Excursion 33D
2019 GMC Canyon

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Old 08-21-2021, 11:06 AM   #2
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With all the problems I see posted on these fancy electric toilets, I am thankful that I have the good old foot pedal operated gravity-drop toilet.

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Old 08-21-2021, 11:21 AM   #3
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If the pump keeps running you likely have a vacuum leak. If the bellows are leaking you likely will have sewage in the compartment.

While the vacuum switch is reliable they do fail. The switch is located on the accumulator tank which is why the pump wouldn't stop running with your hand on it.

If you are lucky sometimes some of the liquid will drain without a vacuum but don't count on it.

Parts are available to rebuild the pump. has some diagrams on their page. Fast shipping and good phone support.

Shaving cream on the fittings will show where the leaks may be. It draws into the leak.

You said: When the vacupump is running and I activate the pressure sw on the tank, pump quits. To me that indicates problem with the vacuum switch OR you have a leak. I have manually turned the adjusting screw about 1/8 turn till I got desired results. It is not recommended so do at your own risk.

I would buy a rebuild kit that includes the bellows, gaskets and duckbill valves. You have no history of the pump, you have been into the bellows and the duckbills are the next suspect. They aren't hard to rebuild, lube the duckbills, dish soap works well, and don't over tighten. Don't overlook the slip-fit gasket that goes into the accumulator tank. Six bucks it might be worth it if you suspect it.
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Old 08-27-2021, 07:07 AM   #4
Join Date: Oct 2019
Location: Dewitt, Mi
Posts: 44
Dometic VacuFlush

I rebuilt the Vacuum pump. Replaced the bellow which was compressed (vs expanded) I dont see any leaks. Toilet bowl water stay in the bowl all this time. After rebuilding Vacuflush pump, even though the pump would not quit, I flush the toilet and the water on the toilet went down without the vacuum sucking noise. If the Vacuflush is running ( and I assume creating vacuum) would it still create the sucking noise even if the switch is bad? or the vacuflush pump will not create vacuum if switch is bad?

Next I might replace switch, if I cannot get any repair shop

2014 Fleetwood Excursion 33D
2019 GM Canyon
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Old 08-27-2021, 07:30 AM   #5
Join Date: Oct 2019
Location: Dewitt, Mi
Posts: 44
Dometic Vacuflush

I vacuum maintained all the way to the main holding tank? or vacuum is at the toilet bowl to the secondary tank (smaller tank)

2014 Fleetwood Excursion 33D
2019 GMC Canyon
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Old 08-29-2021, 12:34 PM   #6
Join Date: Oct 2019
Location: Dewitt, Mi
Posts: 44
Update on this

After verifying if the pump was creating a vacuum by putting my palm to cover the inlet side tubing (in my case tubing connected to secondary tank or small tank) I found out that pump is not creating a vacuum. I disassemble the Vacuum pump generator and O.E. (operator error) found that I mis-assembled the bellows. The collar to the bellow was improperly installed. Assembled it correctly and before I installed it back I bench tested the Vacuum generator covering the inlet and powering up pump.

Anyway, the reason why the vacuum pump was not stopping was:
1) Bellow was compressed and was not creating vacuum
2) There is a leak at the fitting (rubber seal) at the inlet of the vacuum pump. The seal must have been damaged from dis-assembling the Vacuum generator

Thanks to all who helped
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Old 09-23-2021, 09:40 AM   #7
Join Date: Oct 2019
Location: Dewitt, Mi
Posts: 44
Dometic vacupump


After finding that the vacuum pump was not creating vacuum, I tried the shaving cream method. (I can hear leak hissing but do not know where). I found that the leak was coming from the pump adapter to diptube fitting. see link. The first o-ring was rolled. A $1.46 part. replaced and now vacuum pump shut off all works
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Old 09-23-2021, 09:54 AM   #8
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Location: Texas Hill Country
Posts: 800
Installing the bellows incorrectly seems to be a common mistake. Glad you got it done! The VacuFlush systems are not as scary as people think they are. It's nice to know that you can fix it yourself.
I carry a box of brand new VacuFlush system parts in case I ever have a problem when on the road.
Just for reference, this is what I carry for VacuFlush spare parts. Most if not all, is available on Amazon or Ebay.
1) 385311462 Seal kit
2) 385318162 Ball kit
3) 385314349 Water Valve kit
4) 385310063 Floor Seal kit
5) 385310540 Vacuum Switch kit
6) 385310076 Duckbill Valves (2 kits for a total of 4 valves)
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415cid V10 gasser / 6speed / Dana S130 with 5:38's
Towing 2018 F-150 Lariat 3.5EB / 10speed / 3:55's
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