This is my first time posting to this web site, so I hope someone can help. I have a 1990 Mercury outboard 40HP. I've had it now for approximately 4 years. I had it running and in the water a couple of weeks ago and it ran fine like it always has. Recently I went to start it up and it would crank, but it wouldn't fire over. I replaced the spark plugs and had the same result. It would crank fine, but again it would not kick over. I checked for spark on all 4 plugs and it looks fine. I see gas entering in both carbs, so I know it's getting gas. Does anyone have any ideas as to what it could be. I'm stumped here. I tried everything that I know to do, but this is kind of limited because I'm not a mechanic and I'm not to familair with outboard motor repair. I was hoping to get some help here on this forum. Please help. Thanks.