mercury woes

[mistercinder]

hi

got a 1999 mercury 50 hp 4 stroke 4 cyl on my 1971 fletcher 16 speedboat
engine will tick over and maxes out on fast idle lever (out of gear) but will not rev past 2000 under load
usually stalls when selecting gear
prop is geared OK
using fresh fuel
fuel tank vent open
have checked:- carbs, fuel line, fuel bulb and tank pickup, fuel pump, accelerator pump pipes, auto choke
it's as if it's stuck in limp mode when in gear - will not take more than a quarter throttle then engine bogs down
still getting overtaken by canoes
any ideas?

andy

 

[racerone]

The " basics " must be looked at ------------------Compression #'s are ???-----------------Put a timing light on it and see if you have good spark on all cylinders up to full throttle.--------Valve lash has been looked at ??-----------No broken lifters and all valves operating ???----Were carburetors taken apart for cleaning or did you use a " bit of spray " cleaner ??