I have a 89 Merc 9.9 That runs rough at idle and higher speeds. Lower plug always looks wet/grey emulsion and often small water droplets on.
Compression good at 105 PSI in both, gas is fresh and 50:1
New plugs installed, both getting good spark. (has aftermarket CDI box)
Carb (has carb from an 8HP) was taken apart and was spotless. Fuel needle/seat held pressure for 10 min, float set to 1 inch
Reeds appeared to be good and sealed tight
Float was good and main jet clean
Low speed jet at 11/4 turns out
I have replaced the exhaust cover gaskets and they looked fine, but still same issue. (I could see water in lower with cover off)
Is there any way for water from cooling system to enter the cylinder? I have heard lower seal can let water in, any truth to that?
Compression good at 105 PSI in both, gas is fresh and 50:1
New plugs installed, both getting good spark. (has aftermarket CDI box)
Carb (has carb from an 8HP) was taken apart and was spotless. Fuel needle/seat held pressure for 10 min, float set to 1 inch
Reeds appeared to be good and sealed tight
Float was good and main jet clean
Low speed jet at 11/4 turns out
I have replaced the exhaust cover gaskets and they looked fine, but still same issue. (I could see water in lower with cover off)
Is there any way for water from cooling system to enter the cylinder? I have heard lower seal can let water in, any truth to that?