I have a MERC 402 40H.P. 1975-76 which will not produce power under load.In the driveway with the muffs installed all is fine 5000 plus R.P.M. but once the boat is in the water it will only make 1500-2000 rpm and do about 5mph it used to go 25-30 mph.I replaced the stator,coils and overhauled the carb and fuel pump.Also the remote tank hoses etc are all new and the fuel filter is clean.All the wiring has been fixed of corroded wires etc.I looked at the reed valves no issues,the compression is good both cylinders squeezing the bulb while running has no effect either.looking for help!!
