Bilge pump gets weaker and weaker

[limbodog]

I’m hooked up to a battery charger. Both series 31 batteries are above 90%.

My bilge pump spins up when the float switch comes on, but it seems it is no longer strong enough to push the water out of the boat.

It was plenty strong enough just a couple months ago.

What can make a bilge pump get weak?

 

[ggrizzard]

Voltage drop due to corrosion on connections?

 

[limbodog]

That’s a thought. Clean the contacts and it speeds back up? Will give that a shot

 

[Benny17441]

Either input or output. Possible reasons, drop in voltage due to corroded connections or increased resistance in the wiring, restrictions on water flow due to clogged strainers or clogged discharge hose or simply a fouled pump. My preferred method of testing is to bring battery power directly to the pump with jumper wires. It is kind of an easy way to diagnose if the problem is in the wiring, switches, water flow or the pump itself. It may avoid having to take electrical readings or removing the pump. If upon application of direct power the pump works fine and expels water then the fault is in the wiring, if the pump runs fine but does not expel water then there is a blockage limiting the flow. If the pump still runs slow then replace the pump.

 

[David in Sandusky]

Brilliant, Benny!

 

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[limbodog]

I think I figured it out before even getting that far. The battery charger started putting 6 volts into my battery. When I put it on the meter, it's only cranking about 7.5 volts despite the charger saying it was fully charged.

I think it's time to replace the battery.

 

[SFS]

Did you check the voltage on the battery (as opposed to the output of the charger)? Something is not right, I agree, but you need to make sure you understand what you are measuring before you draw conclusions from your data. Is it possible you have a 6 volt battery?

 

[limbodog]

Yeah, it’s a group 31 AGM deep cycle battery of indeterminate age. I put the voltmeter on it and got 7.6 volts. Just picked up a new battery. Will post results either way, but I’m hopeful

 

[SFS]

7.6 is definitely fried. New battery should solve the problem. Let us know.

 

[limbodog]

I'm guessing I should get used to this.

Ok, I brought the new battery down and wired it up. Success! New electrons are just what the doctor ordered and the pump pumps like a champ.

But in the process, I had to wade into the BATTERY PIT OF DOOM!!

Therein I learned that half the wires under the bed frame (that's where the batteries are) were actually not connected to anything. Took me three hours of hunting and pecking to finally get the wires that mattered connected. But now I am so very confused.

First... I'm not sure if the float is working. It probably is, I just haven't dumped water into it to confirm yet. (maybe this evening) Worked fine before, but what with all the wiring I need to check. I just wanted to be clear about that.

Second. The setup for my bilge pump is: The power panel has a DC on/off switch, that has to be on. The power panel has a bilge-pump on/off switch, that has to be on. The bulkhead next to the panel has a bilge-pump auto/off/manual switch, that must be switch to manual. The 'house' wire (previous owner's label) which appears to provide power to the panel must be wired up. The 'engine' wire (also previous owner's label) has to be wired up. If all of those things happen, bilge pump turns on. I have no idea why I need to have the engine starter powered for the bilge to work. And it means I am drawing from both batteries rather than just one when in the slip, which isn't what I want. I suppose I could wire the engine to the house battery as well until Spring tho'.

So the next lesson is: What the heck is going on with my wiring?? (aka: who labels wiring with duct-tape and water-soluble ink anyway??)

 

[justsomeguy]

Ah, the wonders of a "new-to-you" boat!

 

[DayDreamer41]

@limbodog welcome to boat ownership's trial and tribulations, by the sounds of it you purchased a boat which has many hidden lessons, I guess the only way to look at it is, once you have completed the repairs you will have become that much more intimate with the boat and if something happens you will know exactly where to find and repair the issue.

Sounds like you have to make a wire schematic sketch as you trace the wires out, where are they from and where are they going. If you have a meter you are about to put it to good use, if you don't have a meter then you will need to purchase one that reads, Ohms, AC and DC volts. Reading Amps requires either a shunt be placed in series with the load or a meter which can stand being put in series with the load, the latter of which will cause some extra $$ to be spent on a meter which can accomplish this task.

Sorting out the wiring will be a per wire task, be patient and make yourself a drawing, and as you have already pointed out, get some good tags to mark the wire once identified.

Mark

 

[limbodog]

Thankfully I have a master electrician aunt, and a father who was an USAF mechanic (apparently boats and airplanes have a lot in common)

I figure getting started was the hardest part. I'm going to need to buy a bunch of new connectors as PrevOwner was happy using bare wire tightened under the nuts but I am not.

I also have a door/panel in the floor (what do you call those? Sole hatch?) or two that I can't get open. Not sure if there's a trick, or I just have to ruin it to open it. But they've probably been unmoving for years. But even if I do, it seems the wiring is going to be hard to get at. I'm not sure my boat was built for wiring convenience. Will have to check my manuals and see if it has info on that.

 

[DayDreamer41]

Not sure how helpful this will be, I didn't see any schematic's for the 40 but in general the wiring schematics published are not very useful anyway, as you will find for yourself and you peruse the attached.
https://www.marlow-hunter.com/wp-content/export/Wiring-Schematics/41/z-Service Manual/
Info from this forum - Hunter Owners - Ask a Hunter Owner - Hunter resource documents
As for the cabin sole access covers, I am sure what has happened is the wood has swollen a bit binding the cover in, enough upwards force it will pop loose. I know there are a couple of covers on our boat which are only intended to fit (1) way, as a couple of the corners are rounded, they do fit the wrong way but are a bugger to get out.
If you don't have a multi meter yet, this would be a good time to purchase on. I hope that any of the OP wiring changes were done with marine grade wire, if not I would look at completely changing out the circuit, and yes, the wiring will not be easy to get to that is for sure.
They build these boat interiors on the shop floor and then drop them into the hull, so many of the areas are not easily accessible.

 

[LeslieTroyer]

A tone and probe (aka fox and hound) will be very helpful in finding where all the wires go when you loose sight of them. Decent ones are about $30 good ones about $80. Attach the probe to a single wire and use the probe to trace where it goes.

Les

 

[limbodog]

Oh right! Fox and hounds, forgot about those. I've had one in my amazon list for some time. I guess now would be about right.

I do have a multimeter, but could probably stand to upgrade to one with clips instead of pins so I can walk away from it.

 

[SFS]

Or you may be able to upgrade only the cables, without buying a new meter. I can see that having cables with both types of terminations would be useful.

 

[heritage]

Or buy a couple of these:

https://www.amazon.com/TestHelper-A...coding=UTF8&psc=1&refRID=SVR0TP9DAS5M4F46ME10

 

[Ward H]

The power panel has a DC on/off switch, that has to be on. The power panel has a bilge-pump on/off switch, that has to be on. The bulkhead next to the panel has a bilge-pump auto/off/manual switch, that must be switch to manual.

I'm still new to a boat with an automatic bilge pump but here is what I have learned. Others may correct me if I am wrong.

A bilge pump should be wired directly to your house bank, not to your DC distribution panel. This keeps your bilge pump always supplied with power despite if you turn off the battery switch or DC panel. The power to the Auto - Off - Manual switch should have an in line fuse to protect the wiring.

Auto - Off - Manual switch:
Auto position powers the pump through the float switch.
Off shuts it completely off.
Manual allows you to turn on the bilge pump despite the position of the float switch. On some switches this is a momentary contact switch so you don't turn it and forget it.

The switch should be left in the Auto position so the pump will run whenever the float switch is raised by water level.

Maybe the Auto - Off - Manual switch was an add on by a previous PO and he took the easy way out and ran the power from the DC control panel.
It shouldn't be too difficult to run a new wire from the Auto - Off - Manual switch directly to the house bank and add a fuse. Wiring the switch so the float is powered by the Auto position and the pump runs in the Manual position might take a little tinkering. It may be the wiring on the back of the switch or at the pump. I'd start at the back of the switch.