Hi, I have a 1985 Evinrude 50 hp and I have just got it from a buddy of mine. It sat for about a year and a half (i believe with no gas in the carbs). I replaced all of the fuel lines and fuel filter, i cleaned the carbs out really good and my buddy had completely cleaned out the tank. I replaced the champion plugs that were in it with NGK plugs. When I got the boat, the motor would start but not idle. After I cleaned out the carbs I got it idling and it seems to run decent it with maybe a slight miss. I really can't tell. So I put it in the water after I have got the engine to idle and warm up and when i put it in gear it wants to die. Once I do have it in gear and it stays running (which is not often) and I put it full throttle the boat barely does maybe 5 to 8 mph. Its on a 15' Challenger bass boat that weighs 575 lbs. so it should def move faster than that. So I have two questions. 1) If my compression is good, what could be causing this? 2) The two carbs are connected by a linkage, is there a way to sync them together or should the linkage automatically put them in sync with each other. A buddy of mine keeps telling me to sync the carbs but I have no idea how it would be done since they are both controlled by the same linkage. Im sorry for such a long post but this is my first boat and first forum so just trying to put it all out there for you. Thanks.
I would start with a couple of simple tests, spark and compression, those engines will run on one cylinder pretty well. If those are ok, try squirting some fuel mixture into the carbs and see if it picks up, you might still have a fuel problem.