Bilge Pump too eager to run

Made it up to Prince Rupert on our Alaska adventure and catching our breath here for a few days before crossing the Dixon Entrance. Three times now after a day’s cruising, I heard the main bilge pump running after turning off the engine. Looked in the bilge but there was no water, it was running dry. Looked at the DC panel and the circuit breaker/switch was off (as normal) but then I noticed that the LED light on the switch was lit even though the switch was off. I turned the switch on (the light stayed lit) and then turned the switch off again. Both the yellow LED and the pump immediately went off. Now that this has happened three times, I figure I better get a fix. I don’t want to burn the bilge pump out (can’t hear it going when the engine is running). Anyone ever had this issue? Maybe a bad circuit breaker/switch? (It is a Blue Sea panel.) Any insights appreciated, thanks.

There's nothing wrong with the circuitry. What you describe is as it should be except for the pump running dry. Sounds like the float switch just needs to be cleaned. The switch functions by sensing the conductivity of water. When it gets dirty it can retain enough water in the filth stuck to the switch that it won't switch off when the water level goes down. Simply mix up a solution of soapy water and scrub the switch with a soft brush. In the interim if you hear the pump running you can cycle the breaker as you did to shut it down. The breaker is actually the direct power to the pump which bypasses the float switch. Something about cycling the power from that side of the switch clears it when it is stuck. Go figure.

Hey thanks, Dan! Just what I needed to hear. Didn’t think that could be the problem since I could turn it off at the breaker. Sounds like an easy fix and I’m optimistic that will do it.

I also make it a habit to periodically clean the pump impeller. The opposite can happen if crud gets in there. It will keep running and not pump the water out. I have also found that my sensor seems to be a bit lower than it should and tends to run too long. I raise it just a wee bit from bottom when slipping it back on after cleaning it and this helps. And I think you found the trick of throwing the manual switch/breaker to on and then off and that will usually shut it down

I wanted to comment on this subject and was going to go back and find a past related topic in the forum. I had the opposite issue over the weekend. I yearly test my auto bilge pumps "the two finger test" I did this over the winter when doing yearly inspections. I have a full cockpit enclosure, I do a regular cleaning of deck drains and keep troughs clean, I have resealed all cockpit deck hatches, I try to maintain a relatively dry clean bilge. I'm not sure that my auto bilge sensors have ever been activated by water. It is still a very important component that needs to be functioning at all times. Over the weekend I was changing a engine raw water fitting and replacing the seal and o-ring for the sea strainer. When I pulled the hose off the water drained into the bilge and the water level was high enough to activate the auto bilge pump but it never came on. I then cracked open the sea cock to raise the level in the bilge just to confirm that the level was high enough. No pump. I tested and clean the sensor contacts over the winter and worked fine (two finger test). Now no operation. I then took a few paper towels and my long nose pliers and wiped the front of the auto bilge pump sensor face serveral times (the sensor was under water completely) After doing this the sensors contacts made continuity and then the pump ran and pumped water out. I then retested by opening the seacock and filled the bilge again the pump functioned as designed. I have read that cleaning the sensor is important and have followed through with this and tested. I have also read many have replaced the sensor because of its unreliable service. I will now make this a monthly inspection instead of yearly. I liked the idea of this type auto bilge pump sensor but now have second thoughts about reliability. In the next off season I plan on replacing the sensors with old school float switches.

I have had to replace my sensor about four times. I had to replace the forward one once.

BB marine":3p46g57l said:

... I liked the idea of this type auto bilge pump sensor but now have second thoughts about reliability. In the next off season I plan on replacing the sensors with old school float switches.

Click to expand...

That's been on my list of modifications for years but it hasn't risen to the top yet. Float switches have their flaws too but it's that old "devil you know" syndrome. I lost my faith in automatic bilge pump switches a long time ago therefore don't consider them to be critical components. If they are unreliable then by definition they shouldn't be considered a first line of defense. Redundant pumps and paranoid bilge management work well. And storing the boat on a trailer 😉

I’ve had the same experiences with bilge pumps as above and have the same attitude toward bilge pumps as above.

In my current Ranger there were sensor/pump issues with the rear one so I changed out both for RuleMate 1500 pumps. They're one piece units that clamp into a strainer base so when it’s time for maintenance/repair you just squeeze and pop the whole unit is in you hand float switch and all.

Besides cleaning bilge pumps the other trick is to squirt water up the discharge line any time you have it disconnected from the pump to ensure the in line one way valve is not clogged.