Need help

[Ryan21]

I have a 1994 Seadoo XP 650. I know that it is old but i had the engine rebuild beginning of last year. On my last ride of the summer last year it was running great, no problems or nothing. It sat in the water for a bit while i was hang out a friends boats. When i went to get back on it had no power, a little fishing boat could pass me if they want to. I sent the engine back and they said the problem, is not the engine. I but the engine back in and now all it does is back fire. Can someone please give me some advice of what the problem may be? I was told the stator may need to be adjusted to a certain point but i don’t see how that will fix the problem. I was also told it could be the time but the engine place said it is good. Could it be the rotator valve? Please Help My e-mail is Hckyrules219@yahoo.com