De-Winterization Problems...

Hello!

I am a complete newby here, and hoping that some of you experts can give me a clue!

I have a 1996 Mastercraft Maristar 225 with the LT-1 Corvette engine. It was winterized last fall, and de-winterized this spring, and now when cranked, it makes an unfamiliar noise that almost sounds like somewhat of a sucking noise. I am wondering if anyone has an idea of what this might be...

I keep hearing that it could be the impeller - where is the impeller in this boat, and where do you hook up the garden hose to run it on a hose out of the lake?

Any help and tips would be much appreciated THANKS!!