410: Bilge Pump prob

[mfotis]

So I have this 1100 GPH bilge pump in my starboard hull that works but doesn't really pump water. It's float activated and when it is removed from the drain line it will pump water all day but when it's attached to the line it won't move the water. I checked the line and it appears to be clear. I can drain the hull with the manual pump that draws the water through the bilge pump and the drain line with no problems. I've disconnected the drain line from the manual pump and ran the bilge pump and got nothing? Anyone else have this problem before? Is it possible that the bilge pump will still pump water when it's easy but no longer has the torque to push the water all the way through the line?

[Kokanee]

Any centrifugal pump such as a bilge pump will have decreased performance if the output pressure is increased by pumping uphill.

When new, your Rule 1100 GPH bilge pump will pump 1100 gallons per hour without the hose attached. When attached to a hose and a thruhull 2 meters above the pump, it will pump only about 500 gph. (when new) because the water "slips" around the impeller.

If the impeller blade is worn, or if the suction strainer is partially blocked, or if the wiring to the pump is damaged, the pump will not be operating at maximum efficiency. It may only pump to a maximum elevation of 1 meter. If your thruhull is 1.5 meters above the pump, there will be no flow.

1. So check & clean the strainer;
2. check impeller blades for damage;
3. check for blockage in your discharge hose;
4. If you have a check valve (non-return valve) in your discharge hose this may be stuck closed;
5. Check voltage at pump when it is running

[mfotis]

Thanks for the reply, I checked and the strainer was good. The wiring appeared to be fine. I did not however check the impellers or the voltage. The through hull for this is level with the cockpit floor and I think it's less than 2M. The port side bilge has the same run and there aren't any problems.

[Sardean]

Ive seen the motors stall or go slow when loaded, I guess due to bearings or internal winding problems. Try putting your hand over outlet and see how much pressure you have. Low battery voltage or poor connection can also cause problems. On nearly all the pumps ive thrown out the impeller doesn't spin freely. Unclip the cage of pump and spin impellor,. Also check for debri or chipped impeller. Good luck

Sent from my D6653 using Cruisers Sailing Forum mobile app

[tuskie]

Originally Posted by Kokanee

When new, your Rule 1100 GPH bilge pump will pump 1100 gallons per hour without the hose attached. When attached to a hose and a thruhull 2 meters above the pump, it will pump only about 500 gph. (when new) because the water "slips" around the impeller.

How do you know the bilge pump is a Rule 1100 impellor type pump? The OP hasn't specified the model. As this thread is posted on the Lagoon Catamaran section, are you familiar with the bilge pump systems of these catamarans? Hint: they are a bit different to most vessels.

Our L400 has standard Lagoon fitment Johnson Viking bilge pumps. These are an electric diaphragm pump, and as such is a "positive displacement" pump as opposed to the "rotodynamic" type normally used. It does not have an impellor or rotor to foul, and doesn't suffer nearly the same flow reduction due to increased head. "Zero head" flow rates of diaphragm pumps are usually lower than similiar spec standard bilge pumps.

Common issues associated with diaphragm pumps are clogged or broken valves, torn or perished diaphragms or electric motor wiring failures.

Many Lagoon owners fail to understand the original design of the bilge pump system and decide to "improve" it by replacing components with unsuitable replacements. Substituting an origin fitment diaphragm pump with a Rule 1100 would be an example of such a detrimental modification.

[rwidman]

Originally Posted by mfotis

..............I can drain the hull with the manual pump that draws the water through the bilge pump and the drain line with no problems. I've disconnected the drain line from the manual pump and ran the bilge pump and got nothing? ...............

First, is this a new problem or has it always been this way? Was anything worked on about the same time you noticed this problem?

If I understand your post, you seem to have both an electrical pump and a manual pump connected to the same output hose. I suspect that's where your problem lies. There's no good way to do this.

[mfotis]

I just purchased the boat a few weeks ago and the bilge pump was inspected but I suspect it wasn't actually put to test with water so it's a new problem to me. I know it's not a Rule bilge but I'm not sure what it is, I forgot to take a pic like I wanted to. I will have to look at some pics of the bilge that supposed to be in the boat and compare. I do know it is red and white like the Rule or sureflo pumps. Unfortunately the boat is in FL and I'm currently in VA. I'm just trying to garner as much info as I can so I can work on it again when I get the boat up here.

[mfotis]

Tuskie could you send me a pic of the pump you're talking about? I'm not sure if I'm looking at the right one online.

[HopCar]

I have seen this problem several times. It will drive you crazy trying to figure it out. When it happended to me I finally figured out that the impeller was loose on the shaft. When the hose was connected there was enough back pressure to stop the impeller and allow the shaft to spin in it. With the hose removed and no back pressure, there was enough friction between the shaft and impeller to allow the impeller to move some water.

Open the pump to expose the impeller, tug gently on the impeller. If it comes off the shaft you've found the problem.

[tuskie]

Originally Posted by mfotis

Tuskie could you send me a pic of the pump you're talking about? I'm not sure if I'm looking at the right one online.

Not easy to photograph our installation in the bilge.

This is is pump we have fitted in each hull.

Johnson Viking Waste Pump

NB. We have a different model Lagoon to yours, and yours may not have original fitment bilge pump system.

Also note that these pumps are NOT submersible, NOT impellor type and therefore not subject to most generic bilge pump problems that well-meaning but misguided posters are addressing.

[mfotis]

Thanks, that's the one I'm looking at but that's not the one I have, I figured it wasn't submersible. I'm assuming that I can just run a hose to the lowest part of the hull and mount this as close to the floor as possible and let it pump the water out. The one I do have is submersible and is float switch activated. I guess I'm supposed to put some kind of strainer on the end of the hose to keep from sucking in stuff?

[PaulinOz]

Quote: from original post:

"I can drain the hull with the manual pump that draws the water through the bilge pump and the drain line with no problems. I've disconnected the drain line from the manual pump and ran the bilge pump and got nothing?"

So you are saying that you have a submersible electric pump that is connected to the manual pump on deck (or wherever it is mounted) via the drain line, then I assume the output of the manual pump goes overboard.

Is that correct?

You then say:The one I do have is submersible and is float switch activated. I guess I'm supposed to put some kind of strainer on the end of the hose to keep from sucking in stuff?"

Submersible pumps are designed to be submersed, they normally do not have a hose on their suction side inlet connected to a strainer. The strainer is usually integral with the pump assembly.

Photos or model numbers would be a big help in trying to understand what you have.

[mfotis]

That is correct, the manual is mounted inside the gear locker aft the cockpit, and just dumps through the bottom of the deck.