Try this---disconnect bilge pump discharge hose and pinch it off. If no water gets in, then you have found the culprit. As for poor bilge pump issues, I plan on using something like Arid bilge. Notice I said like it, cause its $800 so a cheaper alternative is Seaflo Dry bilge system, its around $150. Finally a DIY method is about $50. All three use a self-priming pump that is ok to run dry, a timer of some sort so the thing will turn on for a minute or two every couple of hours (or whatever you think you need) and the the water pickup is basically a sponge enclosed in a holder of some sort. It is not a bilge pump replacement but a device that will get all the water out except for a few drops. Look on you tube or google the brands, you should see a link to the DIY method there. I think I will probably go with the Seal system, when I get my boat.