Livewell problem

I'm a new member so please bear with me.  I have a 1997 Fundeck 196 configured for fishing.  Two swivel chairs on the front deck and an electric trolling motor.  The boat has a livewell which was not hooked up when I bought the boat in 2018.  It has 3 fittings on the outboard side of the livewell which is at deck level, but probably not below the waterline.  There were 2 hoses laying in the bilge.  One had a wye connection with 2 short hoses.  I connected those to the upper fitting and the one immediately below it.  I connected the second hose to the outlet, which had a plug-in pipe inside the livewell.   When I turned on the Livewell switch water filled the livewell and quickly overflowed onto the deck.  I shut off the switch expecting the water level to remain at the top of the overflow pipe, but it drained to within 2 or 3 inches from the bottom.  Apparently it leaked back through the lower inlet port to the pump and out somewhere.  The system is difficult to trace, but there is only one pump.  When the pump is running water also exits a small hose in the engine compartment.  It is not long enough to go over the side, floods the engine well, and leaks thru a hatch into the bilge.  I suspect this hose acts as a siphon to draw the water in the livewell out.  Obviously it's not working properly.  Godfrey/Hurricane has not been of any help with this problem, and I have not been able to find this configuration online.  If anyone has an idea as to what is wrong please answer or email me.  Thank you.