Gremlins in my boat?

So boat has run months perfectly since I got it. 89 Bayliner Carpi with OMC. 2.3L. So it runs great then dies and won't restart even with starter fluid. I cranked and all the sudden it won't stop cranking. I pulled the key and safety out still cranking. Pulled all fuses out still cranking. I had to dang near melt a battery terminal trying to get the lead off..well it did melt. It finally stopped. It was causing a lot of heat or I would have let It crank till it died. Any ideas?

Ok having it done as I am not sure I am up to par but my mechanic says solenoid now if we can figure the fuel problem out too

It may be fuel or it may be spark. Eliminate a spark problem first. Make sure all plugs are firing when cranking. You can use a timing light to do that.

Fuel problem wouldnt cause runaway cranking only the starter or the solenoid can cause that

Fuel problem not spark I just checked spark and changed plugs ect. The fuel water seperator is not all the way full?

Well, OK - did you check that the timing marks line up when cylinder # 1 is at TDC?

Possibly your fuel pick up tube in your tank is clogged. For a temporary fix, remove the fuel tank filler cap and blow low pressure compressed air back through the fuel line into the pick up tube. A permanent fix is to remove the pick up tube and clean the screen on the end of it.

If you have a primer (pump up) bulb, inspect the check valve to make sure it is not stuck or clogged, or replace it. A quick check is to bypass the pump up bulb and see if she starts.