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Thread: Auto bilge pump issues

  1. #1

    Auto bilge pump issues

    Hello,

    I was hoping someone could help me, i have recently installed a new auto bilge pump (Seaflow 750 GPH)

    After installing it and giving it a test, the first half of the output cycle works fine, the second half loses water volume and starts to make a "thum thum thum" noise with a substantially lower output. about 2 seconds before shutoff the pump expels a large amount of water then finishes the cycle.

    IMG_2653[1].jpgIMG_2652[1].jpg

    I am concerned with this, i was of the assumption it should run consecutively until the water level drops i.e. not difference to output flow.

    Can anyone assist?

    FYI, the pump discharge hose runs for about

  2. #2

    Re: Auto bilge pump issues

    By the end of 'the cycle' I assume you mean until/when the float switch turns off the pump? Assuming that it is an integrated pump and float within the enclosure?

    Can you put the pump in a bucket and test it pumps ok until the last inch or so of the bucket?

    Not exactly sure what you mean but I would guess you are referring to the point when the pump starts running out of water. They don't pump as well when the 'suction head' (depth of water that the pump is in) gets below a critical level, where the impellor starts sucking air, making the noise you referred to and losing flow.
    Cheers
    Brendon

    PS. Nice place Poona, well except maybe when the tide goes out and you're a long way from the ramp . A long time ago had a little shack on the beach there, terrific spot with a tinny.

  3. #3

    Re: Auto bilge pump issues

    Suspect Brendon's explanation is spot on and the operation is normal. Not a big fan of the all in one pumps personally - some are a bit to smart for their own good. The current generation Rule pumps as an example basically require a constant charge input to the battery if they are being used on a boat that is in the water permanently as they use periodically run briefly and use current sensing to determine the presence of water on a cyclic basis unlike a stand alone pump and float switch. This means that over time they will flatten the battery. It could be a real PITA if trying to sleep on board too if it's quiet.

  4. #4

    Re: Auto bilge pump issues

    Thanks mate,

    yeah it is an integrated float switch unit.

    to throw a spanner in the works.. it works perfectly emptying a bucket. continuous flow until off.

    it just seems odd that the float switch would be engaging the unit if it was below critical level. would a standalone pump and switch produce a better outcome? it is only being used as a live tank overflow.

    The only thing i can assume now is, A) the angle of the outlet hose is to severe, or B) the mount on the bottom of the boat is not level enough.

    back to the drawing board haha.

    Poona is a lovely place, easy fishing and an easy life. cant get enough

  5. #5

    Re: Auto bilge pump issues

    Option "B" sounds the most likely. As soon as the pump housing gets the first little bit of air into it it will lose/regain prime and start to carry on. The pump gushing water as it stops is the water coming back down the hose. Try leveling it up as a first step but in a situation where there is motion from waves it will always happen to some extent. The individual float switch allows the switch to mounted at a slightly higher level so that it cuts out prior to the point where the pump housing gets air. Are you overflowing a live bait tank into the hull?

  6. #6

    Re: Auto bilge pump issues

    Yes I am mate, definitely a less than perfect option, but the location of the well (front casting deck) does limit me on outlet locations.

    I will keep toying with it and see if I can smooth out the run a bit

  7. #7

    Re: Auto bilge pump issues

    When we set up my BIL's "tournament" style tinnie, ultimately the best option was to break out the hole saws and put an outflow drain through the side of the boat up forward as high as possible. This was with a system that constantly refreshed the water. If you are only draining a tank to the bilge it is not so bad but with a pump pumping in constantly, relying on another pump to get rid of the water, IMO is not a great idea. it would be too easy to get caught up in what you were doing and not realize the outflow pump had stopped until you had a serious issue (been there done that sort of )

  8. #8

    Re: Auto bilge pump issues

    I'm hearing you mate.. I'm going to look at the overflow idea this afternoon.. did you knock a hole through the side of the tank? Or use a stick overflow?

  9. #9

    Re: Auto bilge pump issues

    Through the side with a proper screened outlet to stop bait fish blocking the hole. That way your outlet in the hull can be well above the waterline. If you go with the stick overflow out the bottom of the tank it will have bugger all fall or worse still be underwater.

    http://bla.com.au/default/products/f...h-filters.html

  10. #10

    Re: Auto bilge pump issues

    The upside of a riser pipe is that it allows you to fully drain the tank overboard so long as the bottom of the tank is above the outside waterline, it will drain even if the outlet through the hull is underwater.
    Time for a couple of pictures and measurements.

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