Bilge Pump Running But Not Pumping

[Scout 30]

Originally Posted by John_Trusty

Centrifugal pumps are very simple, so there must have been a blockage in either the input or the output. Since you cleared it by 'jerking' on the hose, you must have dislodged an output blockage. They do not build up much pressure, so it was probably a small blockage that it could not clear. Do you have the inlet filter installed on your Whale Supersub?

Most manufacturers run bilge tubing using wire reinforced vinyl tubing as it is very flexible, cheap, and easy to install in the turns between pump and through-hull. The wire reinforcing presents impediments to flow and allows more blockages. A general improvement for most boats is to replace the outlet tubing with smooth-wall rubber tubing of equal diameter. This is a fun job, considering where the tubing runs, so I recommend flashlights, a box of bandaids, and a thesaurus for cuss words!

I installed the pump & hose. I used the good 1 1/8" Shields Rubber Mulitflex hose with a smooth interior. This was installed about a year ago and has worked fine till recently. The screen pickup is installed on the pump but maybe there was some blockage under it. It's pretty deep in the bilge so I can only see the top of it. I think I'll pull it & see if there's any evidence of something blocking it.

Whale SuperSub Smart IC 1100 Automatic Bilge Pump

[Scout 30]

This pump comes with a built in "non-return" valve and a bleeder valve to prevent air locks. I wonder if either one of those is part of the problem.

http://www.defender.com/pdf/501710_W...ersubSmart.pdf

[boeing1]

could it be the hose, dont know what kind of hose you have on your pump or how old it is, but seem hose walls collapse which could cause your problem

[Sailmonkey]

I'll bet good money that you had an air lock. Somewhere your discharge hose dips down just enough to hold water. Under the right circumstances the water in the bilge can rise without filling the pump housing (caused by the "p" trap in the hose). When this happens the impeller spins but has no dense medium to sling and generate force to discharge the air around the impeller.

Check your hose run for low spots

[Scout 30]

Originally Posted by boeing1

could it be the hose, dont know what kind of hose you have on your pump or how old it is, but seem hose walls collapse which could cause your problem

This is the hose that I used. Seems to be pretty good quality.

https://www.westmarine.com/buy/shiel...11?recordNum=4

[Scout 30]

Originally Posted by Sailmonkey

I'll bet good money that you had an air lock. Somewhere your discharge hose dips down just enough to hold water. Under the right circumstances the water in the bilge can rise without filling the pump housing (caused by the "p" trap in the hose). When this happens the impeller spins but has no dense medium to sling and generate force to discharge the air around the impeller.

Check your hose run for low spots

To be honest I didn't know low spots could cause this. I'm pretty sure there are some so I'll try to eliminate them. Won't be easy but it's a boat so it's not supposed to be.

[Sailmonkey]

Originally Posted by Scout 30

To be honest I didn't know low spots could cause this. I'm pretty sure there are some so I'll try to eliminate them. Won't be easy but it's a boat so it's not supposed to be.

with centrifugal bilge pumps, your best bet is to exit the pump and go uphill to the highest point practical, then run downhill out to the discharge. doing this will mean the hose is clear of traps and ready for the next use without human intervention pump priming.

[Terra Nova]

Originally Posted by Scout 30

To be honest I didn't know low spots could cause this. I'm pretty sure there are some so I'll try to eliminate them. Won't be easy but it's a boat so it's not supposed to be.

Originally Posted by Terra Nova

Perhaps a poor installation with traps in the line?

This should have given you a hint.

[Jetx]

Originally Posted by Scout 30

To be honest I didn't know low spots could cause this. I'm pretty sure there are some so I'll try to eliminate them. Won't be easy but it's a boat so it's not supposed to be.

Before you go to the trouble of uncovering and re-routing bilge hoses, check on that bleeder valve you mentioned. It should make the pump much less susceptible to air lock, but it may be gunked up or blocked somehow. Just pull off the intake strainer (the bleeder is integral to the intake strainer housing) and make sure the ball is free to move and the valve passages are clear.

[Scout 30]

Originally Posted by JEschman

Before you go to the trouble of uncovering and re-routing bilge hoses, check on that bleeder valve you mentioned. It should make the pump much less susceptible to air lock, but it may be gunked up or blocked somehow. Just pull off the intake strainer (the bleeder is integral to the intake strainer housing) and make sure the ball is free to move and the valve passages are clear.

Thanks, I'll definitely do that.

[YellowcakeMan]

I often have the same problem with my Rule 2000. If the bilge pocket is narrow like mine, the level will fall until the pump draws a little air and stops pumping, then the subsequent level from minor drainage is enough to keep the float switch closed, and with the pump air-bound the level won't go down any more. I haven't figured out a solution.

[Sailmonkey]

Originally Posted by YellowcakeMan

I often have the same problem with my Rule 2000. If the bilge pocket is narrow like mine, the level will fall until the pump draws a little air and stops pumping, then the subsequent level from minor drainage is enough to keep the float switch closed, and with the pump air-bound the level won't go down any more. I haven't figured out a solution.

the solution is to ditch the goofy centrifugal pumps for bilge maintenance. keep a big one installed as a de-watering pump, but use a diaphragm pump mounted remotely to pull the water from the bilge.

[Nightcrawler]

Originally Posted by YellowcakeMan

I often have the same problem with my Rule 2000. If the bilge pocket is narrow like mine, the level will fall until the pump draws a little air and stops pumping, then the subsequent level from minor drainage is enough to keep the float switch closed, and with the pump air-bound the level won't go down any more. I haven't figured out a solution.

Yeah, we ended up turning it off and on with the helm toggle switch to get it to settle down. The new float seemed to help. Always wondered what it did on it's own when we were off the boat before I replaced that float.

[Ken Z]

check for debris in pump and or strainer, replace pump😁

[nic26]

Since it has not been mentioned here until now but I had my fun with it over quite a period of time: measure the voltage that arrives at the pump and check your electrical connections and the status of your batteries. I had the bilge pump running but not pumping because it only got about 8 Volts (I think it was).