Mercury outboard vibrating vigorously!

[Greg7]

I have a 2008 Mercury 90 hp 4 stroke, it vibrates vigorously upon starting and cuts off when put into gear. I have had spark plugs replaced,all sensors checked and fuel injectors cleaned and rebuilt and it still will not run. I am open to any suggestions.
Thanks!

 

[Texasmark]

Re: Mercury outboard vibrating vigorously!

Apparently you are dropping a cylinder or more. I can't help you on the fuel injectors, but you can get a battery operated timing light and hook the sensor to each spark plug wire and find out if you have spark on all cylinders. Load in N and in gear are much different and at idle in N most times you can't tell which are hitting and which aren't.

Mark

 

[Faztbullet]

Re: Mercury outboard vibrating vigorously!

Sounds like it my be ignition related, check spark at primary to coil as 1 coil fires 2 cylinders on these engines. If both coils check good then do a leak down test as it may have sticking valve/s. I have seen 1 broke crank on these models.