I have a 1989 Classic Fifty 45H.P. Mercury outboard, when out on the Lake I have full throttle and not really getting the full power of motor maybe 15-18 mph, however if i shut off the fuel pump i get much more power and get it up to 22-25mph I have the motor on a 17' Glastron, and the motor also planes out much better anything will be helpful, thx