2016 Mercury 90 4 Stroke Shaking Missing

[luigirox]

I have a low hour 2016 Mercury 90 that seems to be missing or hesitating. It shakes during idle.
Its almost like its its missing. I was on the lake and noticed this. At higher speeds it seems to do the same where it will miss/hesitate. It was fine on March 2nd of this year.

What I have done -
Changed plugs and the fuel filter.

Any help or advise would be great.

 

[luigirox]

Here is a video - but its hard to see in this one. But you can see it shake at certain points.

 

[ThomW]

Are all the plug wires back on nice and secure?

 

[luigirox]

Are all the plug wires back on nice and secure?

Yea- It did this before I changed the plugs.

 

[QBhoy]

Got to be the fuel that’s bad ?

 

[luigirox]

Got to be the fuel that’s bad ?

Well I thought of that but the gas was put in in March 1st-
And it ran fine then.

 

[QBhoy]

Well I thought of that but the gas was put in in March 1st-
And it ran fine then.

I’d still not rule it out. Could have been diluted with previous bad gas.
Other explanation is that it’s drawing air from somewhere. Around the filter or fuel connection perhaps ?
Do you have a pre filter or just the one under the cowling ? There is also a small strainer on the injection rail too. If your filtration hasn’t been ideal perhaps. Think it’s recommended to check that every 300 hours. (I have the 115 version of your engine).

 

[ThomW]

Yea- It did this before I changed the plugs.

I'm just trying to think of obvious silly things that may be your problem, if you only changed plugs and filter and now have problems.

Did you make sure plug wires are secure back on the plugs after changing the plugs?

When you put new gas in in March, was the old gas left in the tank too?

Did you install the fuel filter the correct way with arrow pointing with the flow of gas?

 

[QBhoy]

The bottom plug can be very awkward to get to and also to get the lead back on properly too, on occasion.