I have two bilge pumps minted traditionally in the bottom of the bilge but I also have a pump mounted in the bilge “3.8 gpm bilge live well pump” that has pickup at the lowest point of the bilge and has the output plumbed to a side discharge out of the boat what is this pump for?

Not sure what boat you have but it's likely a prior owner hated how cig mounts their bilge pumps 6 inches I the air on a shelf so they wired in a third to get ALL the water out. A better solution is making sure you don't have any leaks in the boat. Should really be any water in the bilge under operating conditions. Rain is another story

I always get some water from the pin in my silent choice y pipes... can t find a fix to this... but in fact i hate that some water stay in the bilge... always take the drain plug off when going out of water... each times!

I have a 99 gun. I believe your right the pickup to the third pump is lower than the other two. But after running it for a season never ran either of the pumps and never acquired enough water in the bilge to worry about it. It looks as if the third pump was factory installed for the way that it is plumbed and the lines are routed.

Mine is a 96 Top Gun and its a Lip-Ship boat, it has the third pump with a line plumbed to the lowest portion of the bilge and it works if you put the starboard bilge switch on the dash in manual. It discharges out the side where the other two bilge pumps do. Its definitely a better set up than the other two!

The third is like all have said, to get the residual water from way down low. I do believe it's also the auto bildge that gets left on the float if you overnight the boat.

Ok thanks guys!

Same here. I've got one that the previous owner installed on my Bullet. While I kept the boat on the lift it was great to keep all the rain water out since I couldn't pull the plug.