Shower Sump mystery

Crushin It

Crushin It

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Oct 10, 2006
1,712
Safe Harbor Marina Kent Island, MD
Boat Info
2006 44 DA
QSC 8.3s
Engines
Cummins QSC 8.3s 500HO
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My shower sump has me stumped. during a shower it Comes on goes off comes on goes off working as it should. Then after 5-10 cycles the pump comes on but does not discharge the water. So now the pump is running and the shower sump box begins to overflow. I have installed brand new pump, float switch and the non return inline valve. The only way for me to get the water to flow is to disconnect the inline valve from the discharge hose and then connect again and it then discharges until another couple rounds again.
 
When the pump comes on do you know that it discharged the water overboard? Almost sounds like it is filling up the discharge line until the pressure builds up, with the check valve holding back the water.
 
I suspect a restriction or pinched discharge hose. Can you follow it all the way to the discharge port? Can you disconnect the discharge hose a blow some low pressure compressed air to make sure it's clear. Shower discharge hose can get blocked with hair.
 
I can try to blow some air thru the discharge hose. If hair is in there would it blow thru? I do not know if there are any screens within the discharge hose
 
You can also connect a shop vac to the discharge hose after the back-flow and try to suck any debris out.
 
Not necessarily your problem but I noticed your float switch has been moved from the factory installed upper level to the lower level. I experimented with this myself and it didn't go well. Mine is now back on the upper level. My line is long, so the water left in the line when the float switch stopped ran back down into the sump just enough to trigger the float switch again. The pump then pumped it out to just refill the line but not out the boat, and then the float switch dropped and turned off the pump. The water then ran back down the line and the cycle started over. My pump was running every 10-15 seconds for a short while because of this. So the designers knew what they were going with the float switch on the higher level. But it does mean the sump is always half full or so of the nasty water.
 
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ZZ13 said:
Not necessarily your problem but I noticed your float switch has been moved from the factory installed upper level to the lower level. I experimented with this myself and it didn't go well. Mine is now back on the upper level. My line is long, so the water left in the line when the float switch stopped ran back down into the sump just enough to trigger the float switch again. The pump then pumped it out to just refill the line but not out the boat, and then the float switch dropped and turned off the pump. The water then ran back down the line and the cycle started over. My pump was running every 10-15 seconds for a short while because of this. So the designers knew what they were going with the float switch on the higher level. But it does mean the sump is always half full or so of the nasty water.
Click to expand...
+1... the problem could be air lock or not able to prime maybe because of the lower float switch
 
Your pump is getting air locked. I had this exact issue on a brand new Rule sump box I just installed. Called Rule and they admitted it was a design error and marked me a new one. Only difference was the float had a 1" spacer under it, preventing the air lock.
 
firecadet613 said:
Your pump is getting air locked. I had this exact issue on a brand new Rule sump box I just installed. Called Rule and they admitted it was a design error and marked me a new one. Only difference was the float had a 1" spacer under it, preventing the air lock.
Click to expand...
So do you always have 1” of water in your box? And to
Clarify was your float switch on the lower level and that had the 1” spacer?
 
villain style said:
So do you always have 1” of water in your box? And to
Clarify was your float switch on the lower level and that had the 1” spacer?
Click to expand...

Here's the sump box I have... different style but same function.

https://www.defender.com/product.jsp?id=4563636

I replumbed my galley sink to drain directly overboard vs to the sump, which is why I bought a new sump. First one came in exactly like the original, but with a newer designed bilge pump in it. After it air locking and reaching out to Rule, the replacement they sent me has the float up about .5-1" on a plastic block, preventing the air lock. Shower sump has never been dry a s the a/c condensation flows to it and we shower on board weekly.

Just an idea that may fix your air lock issue. I started a thread on here about it, someone suggested to drill a small hole in the bilge pump outlet to help prevent the air lock.
 
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I would remove the check valve. Almost bet it will solve the issue. Those check valves cause me issues on a ton of boats I manage.
 
villain style said:
View attachment 75112
This is interesting. Is this the place the hole would be drilled? Not sure I will do this before experimenting with raising the float switch first.
Click to expand...

Correct. Fixed the problem, however since they sent me a new sump I put that in, epoxied the hole and have it as a spare now.
 
Going along with what Bill started and others have said... it does indeed look like the float switch is newer (has been replaced) and was originally mounted on the upper section of the box's floor (two holes). In your parts manual, it also shows the float being mounted on the upper section. Chances are, if you put the float back in it's original location - or just raise it with a spacer block - you should be good.
 
I have always been under the impression the reason the sump has an upper & lower section, is to allow soap suds from showering a chance to "dissipate" before being pumped overboard. No one wants to see a milky, bubbly trail originating from their boat. Putting the float in the upper section accomplishes this, as well as giving more net positive suction head (NPSH) on the pump. When the float shuts the pump out, the intake grates are still well submerged in the lower section.

Jaybeaux
 
Thanks for all the great info and suggestions. Yes, originally the float switch was mounted up top but I thought what the hell, I'll make the pump work a bit more with the float switch mounted down below and keep the whole sump box drier... That was the thought process anyways...
 
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