View Full Version : Bilge Pump Float Switch

06-16-2013, 06:50 PM
Hey gang, I was looking at my bilge pump the other day and noticed it has a float switch on it. The pump turns on and off with the switch on the dash regardless of bilge water level. When I articulate the float switch with it on nothing changes. Does anyone else have a float switch on their bilge pump that doesn't do anything? Or a float switch that DOES to something? Just hoping to compare notes before I start pulling stuff out and replacing stuff.

Thanks guys.

06-16-2013, 07:36 PM
My bilge pump pump has a little knob on the side that you can rotate to turn the pump on and off from the pump itself. My dash also works the switch. It sounds like to local switch doesn't work on the pump. Can you try filling up a coffee can with water and put the pump in there and see if it comes on and off on its own, if it doesn't then you need to change it. You want that thing to turn on by itself without you there, just in case you have a slow leak around they shaft packing or if it rains really hard.

That's my .02 hope it helps

06-16-2013, 08:12 PM
Either your bilge has a built in float, or you have a separate float.

If you have a separate flaot, those can either malfunction or the wiring can become disconnected, corroded, or what not. Check the wiring. If wiring is okay, the switch has probably malfunctioned. You can replace just the switch.

If your bilge has a build in float, then basically if it's malfunctioning then you replace the whole unit. Check to make sure nothing's stuck in or around it, causing it not to fully actuate.

I was a little confused by what you were saying, but it sounded like the switch on the dash was on (bilge running I assume) while you were trying to actuate the switch? Sorry if I understood wrong. But if that's the case, your bilge switch on your dash shouldn't be on when you try to actuate the float. That's the purpose for the float, which is basically just another switch for the bilge.

06-17-2013, 12:38 AM
Wax, you got it right. The dash switch operates the pump as expected, on-off. It was not on when I discovered the float switch and when I articulated the float switch all the way up (like water in the bilge) nothing happened. I've heard the float switches can go bad. Mostly I'm just wanting to verify that someone else has a Moomba with a bilge pump with a float switch for fully-automatic operation. I want to have a clear idea of what is "supposed" to be there before taking action.

06-17-2013, 01:31 AM
BIlge pump used to have three wires, a ground, a hot to the float switch and a switched lead from the dash.

06-17-2013, 10:15 AM
Even if you weren't supposed to have it (which I'm pretty confident you are), it's always best to have a float switch. My 2000 Supra even came with a separate float, when it went bad I just took it out. I didn't live on the water anymore so it wasn't a big deal, I just got used to turning my bilge on every 10-15 minutes. I planned on putting a new one in, but never got around to it. If your boat ever sits in water unattended, you should definitely have one. Even if not, it's a good thing to have so you don't even have to think about it. They make separate switches, but it's easier just to install the unit with the built in switch. My mobius has an automatic bilge unit.

06-17-2013, 10:31 AM
John, yes there is supposed to be a float switch for fully automatic operation. Mine is blue box right next to the bilge pump. And a correction on the dash bilge switch. The positions aren't really "on" and "off", it is more "on" and "automatic". It takes more water that one would think to actually trip the float switch, I think I read somewhere that the float switch needs 2" of water to trip it. There may be a way to adjust it? It does sound like you float switch is dead. I think mine might have died this winter too, as I haven't seen mine trip on automatically yet, and we dunk the bow frequently. Last year is was working perfectly. Although I did tighten my shaft packing before this season, which helped a lot.

06-17-2013, 11:00 AM
The blue box is the same one my Supra had. That's a separate switch, not an integrated bilge switch. It does seem to require a lot of water.

06-17-2013, 12:08 PM
Thanks for the input. I had been wanting to put in an automatic bilge pump that responds to a switch on demand ("on" "auto" like this one is supposed to do apparently). Should I just get a new float switch for the existing set up or should I get a whole new automatic bilge pump? Are the unitary automatic bilge pumps more reliable than a split pump and float switch set-up? Also, has anyone put in a second bilge pump for a backup or as a "lag" pump to increase pumping capacity if you're taking on water a little faster? I like redundancies on the water where I can get them.

06-17-2013, 12:10 PM
I'm sure no one else has ever done this but I launched my Outback one time without putting the plug in. I remember thinking, "Why the heck is the bilge pump running already? . . . DOH!!!!!!!!!" I was very glad I had thoroughly cleaned the pump screen and the float switch. Popped the doghouse open and put the plug in. Never should have mentioned it to my wife because she ALWAYS asks about the plug now.

06-17-2013, 02:22 PM
I don't know if a bilge/switch combined unit is going be more reliable as I'd assume the difference would be negligible, but if either goes bad you have to replace the entire unit. With the separate setup, you can replace one or the other if they go bad. However, if I remember right, the switch is around $40 and the unit with both is about $60. You may be better off just going to the entire unit together, both for ease of installation (no separate wiring for the switch) and simple troubleshooting (if it's bad it's bad, take off and replace). Most new boats come with the combined unit, I don't think the separate switch is very common anymore.

I personally think a second bilge is overkill, and I have never been in a situation that needed one. However, I do have a pump for my extra ballast that I could use in a dire situation lol! If you were in a situation that required a second bilge to keep the boat floating from the amount of water coming in, I'm pretty sure you'd have some other serious issues and it would be time to abandon ship!

06-17-2013, 04:48 PM
Yea, I know a second bilge pump is overkill but stuff happens and that one time something a little exceptional was going on I would be glad it was there. Even if it was just to buy some time.

The pump in the boat is pretty good, I guess I'll replace the float switch to regain original operation so I don't have to rewire anything.

06-18-2013, 01:57 PM

You could opt to replace the entire unit, and then upgrade to a bigger one. That would take care of both of your concerns at once.

I think mine is a 500gph unit. Looking online, these draw less than 2 amps, 1100pgh ones seem to be common too, and they appear to be less than 4 amps, so it should be a pretty direct swap without any electrical issues. The outlet is bigger though, so the line and/or thru-hull might need to be enlarged.

06-24-2013, 05:00 PM
I could see replacing the whole assembly for a fully automatic pump. I'm planning on ordering something today. Do the fully automatic pumps have a manual switch option? I would like to retain the "on" "auto" intent of what I have now. If not, what is the best float switch to use? I keep reading they fail all the time (mine did!).

06-24-2013, 05:35 PM
I added this one to my boat, so I have 2...I have a wet slip and wanted to be able to sleep at night.. :)


06-24-2013, 05:52 PM
Awesome. I just ordered the same pump in 500GPH and plan to install as a second pump with constant power. I'm going to Havasu in July and will be in a wet slip for 3 nights - a good night's sleep was on my mind as well.

06-24-2013, 06:27 PM
Protip.. Splice it into the existing wires so you can use the dash switch for both pumps, The constant and switched power wires were reversed on mine..

Sent from my Nexus 4 using Tapatalk 2

06-24-2013, 06:53 PM
Thanks for the heads up on the reversed wiring.