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Bizarre bilge pump mystery

Jan 13, 2015
59
Hunter 34 Deep Bay, BC
I have a 1983 Hunter 34 (irrelevant to the topic, but I love to talk about my boat) that has a weird bilge pump issue.

When I got the boat, it had a RuleMate 500 pump. This is the type with the internal electromagnetic level sensor with no moving parts. It is wired directly to a Rule Model 41 switch. The switch is wired directly to the house bank. All the connections are correctly crimped and covered in heat shrink tubing, and no connections are ever submerged. I have followed all the wiring, and there are only connections at the ends. This pump would operate erratically; sometimes working correctly, sometimes it wouldn't start when it should, sometimes it wouldn't shut off until I manually turned it off and back on (Auto). It seemed to help if I kept it clean, but that may be conjecture.

I got tired of this, and, on the assumption that the pump had failed, replaced it with a larger RuleMate 750. It did the same thing, although originally not as much. Then after about 6 months it began running for 2 to 5 seconds at random intervals between 10 minutes and an hour apart, then shutting off. I found that if I turned it on manually, it would blow the (correctly sized, 5A) fuse. It was not blocked, as I could freely turn the impeller by hand. I concluded that this pump had failed too.

I replaced that one with an Attwood Sahara S750, which has an internal mechanical float switch. It seemed okay initially, then started the random short runs that the previous pump had, at similar intervals. This time it did not blow the fuse when run manually.

Okay, so it's not the pump. What's left is the wiring (very clean, done correctly according to the diagrams supplied with both the pumps and the switch) and the switch. So I replaced the switch.

Note that throughout this debacle, when the bilge pump runs the indicator light comes on.

AND it's still doing it. And I have nothing left to replace. What the H*** is going on?
 
Oct 24, 2010
2,255
Hunter 30 Everett, WA
Get yourself s multimeter and use normal troubleshooting procedures. Connect it to the pump wiring as near to the pump as you can. Or better yet if you have a clamp-on DC ammeter. Try to not disturb the wiring any more than absolutely required.

When the pump is on (add water if you need to to turn it on,) monitor the voltage (or current) and look for sagging voltage. If it sags more than a volt or two, you have a corroded connection to find. Visually you may never see it. If full voltage is present the problem is in the pump.

Ken
 
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Tom J

.
Sep 30, 2008
1,635
Catalina 310 Quincy, MA
Have you checked the ground connection for the circuit? Sounds like an intermittent connection on the hot side, as Ken described, or the less obvious negative side.
 
Jan 22, 2008
52
Gulf 29 Little Current, ON
I had erratic performance from a bilge pump and determined that all of the water was not exiting through the outflow hose. Some water would come back to and through the pump and activate it again, and again, and again. This could happen multiple times before enough water was pushed out. Could that be related to your problem? Not coming on when the pump is needed would be a different problem.
 
Jan 4, 2010
870
Farr 30 San Francisco
After 3 tries maybe the problem is you? Or at least your understanding of how these pumps work.. I have one of those Rule pumps and what it does is turns on every 2 min and looks at its' input current . A lot of current = water being pumped if so it pumps until its input sucks air. Unfortunately what happens in my boat is the water in the line runs back through the pump and restarts the cycle so it tends to cycle based on the last little bit of water in the line and a low volume bilge sump. So I think in the end the ratio of the sump area to exit pipe volume determine how well these pumps work
 

capta

.
Jun 4, 2009
3,905
Pearson 530 Admiralty Bay, Bequia SVG
i would bet dollars to donuts one of your "connections are correctly crimped and covered in heat shrink tubing" is not so correct. Heat shrink can hide a bad connection just as easily as protect it. You could start at the battery and redo each connection until your pump functions correctly.
Remember resistance (a poor connection) can cause voltage drop which causes higher amperage, hence the blown fuses. Alternately, the connections in the on/off/auto switch could be bad. It is also possible that a fray or pinhole in the wire allowed it to corrode inside the covering.
If it was my problem, I would save myself all the worry and replace the wire and all the connections. Bilge pumps are pretty high on my list of "must function correctly" items.
 
Last edited:
Feb 26, 2004
21,210
Catalina 34 224 Maple Bay, BC, Canada
Get a stupid float switch and a simple pump and stop messing around with the dumb electronic carp.

story will be over, very soon.

Good luck. :)
 
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Nov 6, 2006
8,769
Hunter 34 Mandeville Louisiana
rbringle has a point.. the 34 came with a check valve in the bilge pump discharge line because the pump discharge hose has to be pretty long. When that valve gets a little dirty, the water that the pump put into the hose will leak back slowly into the (very small) bilge and the pump will cycle again..and again.. and again.. Think carefully about Stu's note.. and in addition, clean or replace the check valve. That constant cycling will quickly kill the auto pumps. The mercury switches work very well but ya can't buy them anymore.. The ball bearing switches are pretty unreliable as well.. consider a switch as noted in Maine Sail's post: http://forums.sailboatowners.com/index.php?threads/bilge-pump-switch.181318/#post-1323699
You can increase the bilge volume by cutting out the false bottom if you haven't done that already.. Good luck with it..
 
Jan 6, 2010
1,520
Catalina 30 Mark II John's Pass Florida
Sabre,

There is alot of good input here from the guys. I do also agree with Stu. I gave up on internal float switches years ago. I now only use a separate float switch & past problems went away.

But getting back to your problem, here may be a thought for you. I have 2 twenty foot lengths of 16GA wire.
I have alligator fittings at the ends. I help my friends when they have problems. Even if everything looks right in the wiring, many times just bypassing the existing wiring with my 20 footers, will reveal problems in the existing wiring.

If with the bypass the same problems exist, I would also look at the pump panel itself for problems & maybe bypass this & see what you get.

CR.
 
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May 24, 2004
6,432
CC 30 South Florida
The Rule Mate is an automatic pump. Why is there a float switch connected to the circuit? At best you would have a conflict between the two switches. Bilge pump switches are considered unreliable and to have two independent ones on the same pump is not good. Listen bilge pumps are not an indispensable system requiring high tech components, so get a manual 500 GPH pump and a float switch and as long as they do the work of expelling incidental collection of water you should be good. Like Stu suggests "stop messing around with the dumb electronic carp" I think he meant "crap".
 
Oct 26, 2009
12
Pearson 323 Rock Creek, Pasadena, MD
I have seen a small piece of hard debris get past the pump and wedge against the lip of the through hull fitting, obstructing the flow and causing the pump current to skyrocket. When the pump was shut off, the back flow dislodged the debris, fooling me into thinking the line was clear when I checked it by blowing through the line. Had to physically disconnect the hose at the through hull to find it.
 
May 28, 2015
237
Catalina 385 Long Branch, NJ
Agree with Stu ... I had a similar set of issues with two electronic float switches (installed at factory) ... swapped out a manual switch and its worked fine ever since.
 
Jul 7, 2015
22
Hunter 33_77-83 Kemah
My 2 cents.
Float switches are problematic.
Upgrade to automatic Rule 1100 gph with the built in computer sensor.
Pump comes on every 2.5 minutes for a brief check to see if there is any water to pump. This gives you an audial confirmation that all is good without having to uncover the bilge. Get them on Amazon for $65.
Next it is usually the ground wire or the float switch.
Use a portable car jumper as a power supply and hook it directly to the bilge pump. If the pump works properly on the independent power supply run a new ground wire. If that doesn't work run a new positive wire.
 
Feb 6, 1998
11,272
Canadian Sailcraft 36T Casco Bay, ME
Remember resistance (a poor connection) can cause voltage drop which causes higher amperage, hence the blown fuses.
Actually this is backwards. With a DC motor, such as a bilge pump, as voltage goes down so does the current, even stall or in-rush current is dictated by the voltage the motor sees. High resistance at the fuse can actually serve to melt the fuse but this is not because of an over current situation just high resistance and the heat developed..

A bilge pump blowing fuses likely has a leak and the bearing surfaces are becoming sticky. As a bilge pump or any typical DC motor stalls or has a load applied the current of the motor goes up. Bilge pump makers size the fuse to intentionally trip if the rotor is over loaded and drawing too much current so the pump does not catch fire.. With a constant power source, such as an inverter, as voltage goes down the inverter draws more current to maintain the same output but with a DC motor as voltage goes down so does current.

Why do you have a float switch on a Rule automatic pump? First you need to get the wiring correct.

Battery positive terminal>fuse (within 7") > AUTO-OFF-MANUAL switch > BROWN wire to AUTO POSITION > BROWN W/WHITE trace to MANUAL POSITION > BLACK to BATTERY NEG.

No float switch...

Once the float switch is removed the scenario I would start with is that the pump may be suffering from drain back cycling due to a poorly designed bilge pumping system.

As a marine electrician customers can't even pay me to install any of the "auto-sensing" bilge pumps. I simply will refuse the work unless they decide to do it correctly. I will also refuse to install any current Rule float switch.

A "properly" designed bilge pumping system for a boat over 25' will look like this.

Emergency Pump = Largest Rule or other centrifugal pump you can physically fit. Pair it with an Ultra Safety Systems Junior or Senior float switch and set both pump and switch at a higher level that keeps them out of routine bilge water. This cuts down on DC corrosion risk tremendously!!. (IMPORTANT: DO NOT USE CHECK VALVES ON CENTRIFUGAL PUMPS)

Nuisance Water Pump = Diaphragm pump (check valves are okay on diaphragm pumps) and an Ultra Safety Systems Junior or Senior float switch set for lowest desired water level. Note: All wiring for electric pumps shall be sized for no more than a 3% voltage drop.

Manual Pump =
Henderson/Whale etc. with no check valve just a strainer.
 
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Jul 7, 2015
22
Hunter 33_77-83 Kemah
Bilge pumps are essential safety equipment keeping your boat afloat if something dire should happen while out sailing miles away from land.
Your 34' boat should have around 4000 gph pump capacity installed. The bilge should have two completely redundant 1100 gph automatic bilge (completely redundant means they do not share wiring, discharge hose or a float switch) pumps and the remaining pumping capacity should be mounted in other compartments like the engine bay which is susceptible to filling with water if a cooling line breaks and the small weep holes to the bilge can not keep up with the volume.
There should also be adequate battery amp hours available to keep all these pumps running for at least 8 hours.
Solar to keep the batteries charged is also a good idea if you keep your boat at a remote location where you do not check on it daily. If a storm comes through and knocks out shore power you will be really glad you installed the solar as a storm is one of the more credible events that could put a demand on the bilge pumps.
 
Sep 27, 2014
57
Montgomery 17 driveway
Perhaps a non-return reed valve near the input end of the bilge hose would prevent back seepage that keeps triggering the bilge pump.
 
Jul 30, 2010
25
Hunter 36 West Chazy, NY / Montreal Que.
The Rule Mate is an automatic pump. Why is there a float switch connected to the circuit? At best you would have a conflict between the two switches. Bilge pump switches are considered unreliable and to have two independent ones on the same pump is not good. Listen bilge pumps are not an indispensable system requiring high tech components, so get a manual 500 GPH pump and a float switch and as long as they do the work of expelling incidental collection of water you should be good. Like Stu suggests "stop messing around with the dumb electronic carp" I think he meant "crap".
 
Jul 7, 2015
22
Hunter 33_77-83 Kemah
A check valve seems like a good solution, but strictly prohibited.
I tried it anyways and it was a failure for multiple reasons, and all of them were not good if you wanted the pump to work.
A scupper valve at the end of the discharge hose is the best approach for reducing water flowing back into the bilge, but does not eliminate it completely.
 
Jul 30, 2010
25
Hunter 36 West Chazy, NY / Montreal Que.
Bingo! Benny is absolutely right. The pump integral level switch conflicts with the external one. Suggestion: leave the external switch on place for the future use and disable it. It will solve the mystery and ... misery.
 
Jul 7, 2015
22
Hunter 33_77-83 Kemah
Since he had multiple problems with multiple pumps from various manufacturers in multiple configurations, I would bet a steak dinner the wiring is the culprit which can be quickly verified with an external 12 VDC power supply connected directly to the pump, thereby bypassing the existing wiring and removing it from the fault tree.