Center tank fills on its own

[Reider]

My center tank will fill on its own just from the weight of the boat in the water.  My guess is some sort of check valve on the pump not closing.  Has anyone had this symptom.  19’ 21 vlx 

[CaptianWeekend]

I have a 19' 25lsv that does the same thing.  Not sure why, but haven't taken the time to troubleshoot yet.  I drain it 2-3 time a day when we're on the water not surfing. 

[604wakesurf]

My 18 21VLX centre tank and bow tank both fill on their own. When boat goes in to dealer for some other work, I'm going to get them to look at it.

[Whitecap]

Anyone know the cause of this phenomenon?  Operator error?  (Hitting wrong switch on MLS screen by accident? )

[04 VLX WINDERMERE UK]

Anti syphon loop valve either stuck closed or not high enough, normally located under the dash area. it needs to be above the lake level on the boat or the tank will fill on its own. if the anti valve valve is stuck, (The anti vac valve is a check valve that lets air into the pipe to break the syphon action) this will allow water to flow from the higher level outside the boat into the tank which is below the water line, even if the line is above the waterline under the dash..

hope this helps.

https://www.bakesonline.com/ballast-anti-siphon-vented-loop-valve-complete-3-4.html   Yours might be 1" ?

Edited October 1, 2019 by 04 VLX WINDERMERE UK

[Weaklink]

wow this has been happening on my '17 21vlx but I thought I was crazy. Thanks.

[skicrave]

Unthread the cap on the top of the Vented Loop, remove the "duckbill" valve and clean it out. Frequently it is jammed with debris from the production process which prevents it from functioning correctly. All of the boats mentioned will use 1-1/8" hose, so that's the correct size to purchase if you were going to replace it for whatever reason.

[Reider]

So i located two of the anti siphon units with the duckbills. Took them apart and checked for debris.  However. These two siphon units seemed to be just for the rear hard tanks. Any one else know where the location of other anti siphon units are for the front and center tanks?  Thanks