I just purchased a boat and when I hit the bilge pump switch and try to shut it back off the bilge stays on. I tried changing the switch and it still stays on. Yesterday I was on the lake and got stuck in the rain and the automatic bilge kicked on and when it had pumped all the water out the bilge continued to run. As with the switch the only way to shut the bulge off is by unhooking the batteries. Any ideas as to what is causing this issue?

It sounds like you have something with the float switch that has gone wrong. This is somewhat common. Look for the float switch on the floor of the bilge near the bilge pump.

If it looks something like this:



Grab or jiggle the axle that the float pivots on and see if that will make allow it to turn off. They can get gummed up with grease/oil/debris in the bilge. You may have to replace it.

Sounds like a secondary float issue.
I had one boat that the float was wired hot, and that sounds the same as yours
Meaning the float kicks in and pumps, even with the main battery switch turned off.
Only way to disable was disconnect battery. This is a must for boats kept in the water!!
So like already stated, sounds like a sticking float.