99 optimax starting issue

I have a 99 150 optimax. My air compressor bracket broke and I replaced the compressor. Now here is the problem. My boat will crank on the muffs every time. It will crank when u first put it in the water but once u start it and run it down the lake when u kill it will not start back. It doesn’t even hit like it’s not getting any fuel or spark. U can take the cowling off or u can trim the motor all the way up out of the water then it will hit about 3 times then crank up. It will do this every time. The prop had to be all the way out of the water or the cowling off. So I think it’s a back pressure issue building up through the prop exhaust I just don’t know where to start. Any ideas?

When the compressor broke did it break the block where the belt tensioner spring sits?

Look at it closely. The tensioner should hold the belt pretty tight.

All that broke was the 2 ears off the compressor where it bolts to the motor. But I will check that.