220HP MerCruiser 5.0 Alpha rough on start up. HELP!!

[Jeremy47]

I have a 2009 Bayliner 225 Bowrider and I do my winterizing every year and I am very particular to make sure everything is done right. I bought the boat new and have never had a running issue with it. This year, every time I put it in the water it starts up and idles fine. I give it throttle and it runs rough and will not come up to speed. It felt like to me it was bad gas, like water in it, because after about 200 yards are messing with the throttle and bobbing in the water it is like a light switch and it just comes to life. It runs like a champ after the first initial problem of the day. I have since drained all gas, changed fuel filter, filled back up with high test fuel and marine grade StaBil. Went out again and it has the exact same issue. And ideas of what it could be?

 

[makomark]

If you don't think it is fuel related, then you need to investigate the ignition system...I'd still be inclined to put a fuel pressure gauge on the fuel rail to make sure there is plenty of fuel being provided...