Hello, I have a yamaha F-90. I replaced the impeller, along with the three gaskets and the two seals below the impeller that are just above the lower unit bearings. I put muffs on it and it won't pee. So I hooked a hose to the engine flush hose attachment. Still nothing. I did put some grease on the impeller. I wondered if that may have clogged a opening. But I still think the flusher should work. Any advice? Should I try to blow compressed air through? HOw much pressure is ok. I did check for mud wasps, and detached the hose. Thanks, Alan