I have a 89 Merc 9.9 That runs rough at idle and higher speeds. Lower plug always looks wet/grey emulsion and with small water droplets
Compression good at 105 PSI in both, gas is fresh and 50:1
Cylinder leak down test at 4%
New plugs installed, both getting good spark. (has aftermarket CDI box)
Carb was taken apart and was clean. 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
[FONT=Arial, Helvetica, sans-serif]I have already replaced exhaust plate gaskets with no better results. When I bough the motor, the impeller was shot, so it may have been overheated at one time...
Some have told me lower seal may be bad. Dealer says he thinks that is unlikely. I[/FONT]s there any other way for water from cooling system to enter the cylinder?
Compression good at 105 PSI in both, gas is fresh and 50:1
Cylinder leak down test at 4%
New plugs installed, both getting good spark. (has aftermarket CDI box)
Carb was taken apart and was clean. 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
[FONT=Arial, Helvetica, sans-serif]I have already replaced exhaust plate gaskets with no better results. When I bough the motor, the impeller was shot, so it may have been overheated at one time...
Some have told me lower seal may be bad. Dealer says he thinks that is unlikely. I[/FONT]s there any other way for water from cooling system to enter the cylinder?