So here is the story up to now. I purchased the boat in June, the engines have always ran great until a recent routine service at a local marine repair shop. The service only was to replace the oil sensor in the engines oil tank (part was new from yamaha), put in new water impellers, replace plugs and lower unit oil. I get the boat back and when we put it in the port engine wont fire right up like it always has.. starboard no problem as it was before I took it in. So I get port engine finally to fire after working the choke and throttle. Run the boat to our cottage about 60 mile run with no issues, engines sounding great. Spend the holiday weekend, use the boat to do some fishing but nothing more than that. We run back home with no issues Monday, Tuesday I get up to go out fishing and the engine does not want to start. I finally get it fire up and it spits a lot of smoke... so let the engines warm up before leaving the dock. Once we get under way I get the RPMS up to about 3900 and the port engine stalls, alarms go off and my TACH is lighting up my temp gauge. So we power down the other engine take of the cover and there is no excessive heat at all.. the oil however in the engine oil tank is down to about 1/2, so I manually pump oil into it and try to restart.. it clears the alarm and fires right up and we head back on our way. No problems running from that point on during the day. So we troll and keep my port engine shut off and not in use. When I go to start it back up the engine again bogs and takes some work to get started, it finally fires and lets a big puff of smoke out. So we head in... Now this morning I go to start it up to pull the boat from the water and do some cleaning etc etc. The port engine this morning wont even try and fire up. The fly wheel will not spin and im getting more of a humming/ hissing sound coming from carb area. After a few tries I did get one sound that was almost a stretching, but that quickly stopped and then nothing. And now that brings me to the web to start getting some advise or thoughts. I appreciate any input!