Outboard sputter

[Macker13]

Hi all

My 30hp 2 stroke was stored for the majority of its life so only has 16hrs on it. It's like new under the hood with grease and stickers all like new in there.

It does however sputter on medium revs. Starts fine, ticks over fine and goes fine onto a plane when on water. It's just at low medium revs the main issue it sputters like it misses a beat.

I have put a can of sea foam through it to clear the carbs and also changed the spark plugs. Neither made any difference. Also changed petrol out for complete fresh tank full. I've changed fuel line and tank too.

Yesterday I disconnected 2 plugs at a time to run it on one cylinder and fiddle with the mixture screw. Top 2 cylinders run lovely. Bottom one would tick over a bit then kept coughing white smoke and dying no matter what mixture setting.

What could it be? Could it be the Fuel pump? Sometimes the primer bulb goes soft while engine is running which seems odd but doesn't improve if I squeeze the bulb. Fuel filter is clean. Could it be bottom carb dirty? Seems odd it goes ok onto a plane on water.

Anything you guys can suggest??

 

[jbuote]

Hey there!!

​First off, I am very new to outboards, and there are many pro's here who can help you better than I can.
​I'm sure they will be along very shortly...

But, Until then... .

​Have you taken the carbs off and cleaned them? Have you done a compression test? Have you Checked spark?
Sitting in storage, even a new engine with 0 hours would need an overhaul to carbs, water pump, etc..
​At least as far as I know.. Again.. I'm new, so others would know better..

​Pretty sure you do not run on 1 cylinder at a time to adjust the carbs.. Usually, you run on all cylinders and adjust carbs one at a time..

​White smoke usually would mean water in the combustion chamber.. i.e.. Head gasket..
​Blue(ish) smoke is oil.. Normal for a 2 stroke..

​I have to ask.. I see you've posted this in the Yamaha section as well. Stated there, that you have a Yamaha engine..
If so, this Johnson/Evinrude section is the wrong place to ask..

So, Is it Johnson/Evinrude or Yamaha?

​Again, I stress I'm no expert, but I hope it helps.. Even if just a little..

 

[F_R]

A 30hp with 3 cylinders isn't a Johnson or Evinrude, is it?