Hi there,
I've bought a very nice Fairline Vixen 19 feet boat with a Mercruiser MCM 120 with a pre-alpha drive.
Engine starts and runs really good at low RPM's but won't rev much higher then 3000 rpm at WOT under load (Also won't plane as it only reaches 11mph max).
In neutral it does rev up but only when you throttle up slowly because if you throttle up too quickly it stalls.
I have already checked a few things...
My first thought was a lean condition so I checked the mechanical fuel pump for diaphragm failure, but aside from some nasty stuff it looks fine so I cleaned it put it back. Next thing was the carburetor which was full of nasty stuff. Thought ooh thats the problem but after a good clean and compressed air the problem is the same...
Next thing I did was checking and replacing the spark plugs and thats where things got weird because all 4 spark plugs were pitch black
They don't look oily so I guess it's just carbon which tells me (If im correct) that the engine is running too rich instead of too lean. I've replaced the plugs for some new ones but the problem is still the same...
Does anyone have any thoughts?
Cheers!
I've bought a very nice Fairline Vixen 19 feet boat with a Mercruiser MCM 120 with a pre-alpha drive.
Engine starts and runs really good at low RPM's but won't rev much higher then 3000 rpm at WOT under load (Also won't plane as it only reaches 11mph max).
In neutral it does rev up but only when you throttle up slowly because if you throttle up too quickly it stalls.
I have already checked a few things...
My first thought was a lean condition so I checked the mechanical fuel pump for diaphragm failure, but aside from some nasty stuff it looks fine so I cleaned it put it back. Next thing was the carburetor which was full of nasty stuff. Thought ooh thats the problem but after a good clean and compressed air the problem is the same...
Next thing I did was checking and replacing the spark plugs and thats where things got weird because all 4 spark plugs were pitch black
They don't look oily so I guess it's just carbon which tells me (If im correct) that the engine is running too rich instead of too lean. I've replaced the plugs for some new ones but the problem is still the same...
Does anyone have any thoughts?
Cheers!