Float switch cycling bilge pump too much

[Lively1]

I have a Bayliner 1850 open bow with I/O. I installed an float switch under the engine to turn on the bilge pump if there is significant rain while I'm not there, which it does.  The problem is, when the water is nearly all gone, the pump pushes water part way up the discharge pipe, and the water runs back down again and pump kicks in again to clear it.. etc etc etc. Until the battery is discharged. The float switch is an inexpensive one (Attwood or Five Oceans or such), but it does turn the pump off when I manually cycle it.

 

How can I get the switch to turn off and stay off until the water comes up another inch or two?  I don't need to get every last drop out, I just want it to keep the water level below the bottom of the engine.

 

Would a new higher quality float switch help?

 

Would elevating the switch an inch or two help? (It's flat on the floor of the motor well now).

 

I considered putting a drain in the bottom of the motor box that I could open from inside the boat (since I keep it on a lift out of the water), but several people told me to think twice about that.

 

Thanks as always.

 

 

[anytime]

An inline check valve would solve your problem.

[TileMan Dan]

X2 to anytimes post

[Lively1]

Aha, you mean a check valve on the outlet hose so once the water exits the pump, it stays in the hose vs. running back down into the bilge..  I see how that could help.  Should it be installed close to the pump where the hose is horizontal, or further away where the hose becomes more vertical? 

[Lively1]

Did some further reading. Check valves aren't recommended on centrifugal pumps as they have trouble working against the pressure of the water caught in the outlet hose. True or not?

[guffins fisherman]

Elevate your float switch an inch or so. You will have a little more water in your bilge, but it will most likely make room for the backflow out of your discharge hose.

[Firechief48]

I would also install a check valve. Pump should have no problem as you don't have a lot of head pressure to pump against. I had the same problem with my house A/C condensate pump, I didn't realize when I cleaned it I dropped the rubber check valve, once installed again no problems.

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[RSF]

Hope you don't have a fume or gas leak while away..I don't trust pumps turning on/off on their own. Especially I/O or I.

[Don Supon]

IMO, raising the pump an inch from the bottom will not do anything. Why? Because the rain water will still enter the bilge and activate the pump, but at an inch higher level. With water draining back to the bilge with pump shutoff, the same conditions exist because the pump could not expel the one inch of water left by raising the pump an inch. The check valve sounds reasonable.

[guffins fisherman]

At the risk of splitting hairs, I said raise the switch, not the pump. Quite often they are separate units. A check valve could work too. Never tried.

[TileMan Dan]

Most newer bilge pumps do not utilize a separate float switch. Backflow valve would probably be best in the situation.

Edited October 9, 2015 by TileMan Dan

[Adk1]

Definatly, u need to have the switch above the intake of the pump at least an inch maybe even 2. Otherwise it will always be tripping and activating the pump, which will eventually burn out