Honda BF40 low power output

I'm having problems with my Honda BF40 motor. I have it mounted on a small 14 foot boat and it doesn't go over 25 MPH. I've done everything I could think of to this motor. I think the problem is with the carbs / fuel delivery. It seems like it's not getting enough fuel under load. If there's anyone with the same issue and has a solution, please leave comments. Thank you