2006 Johnson 140hp four stroke

[Fisherman45]

On my 2006 Johnson 140hp four stroke Last time out I started up the boat like normal and slowly moved out of the no wake zone and noticed it running a little rough and gave it more throttle and it wouldn't go over 10mph even at full throttle, it normally tops out at around 48mph. I have used it 30 times this summer with no problems until this last outing. I plan to look at fuel line and pump ball first and the plugs second. I have been using seafoam with every fill up since I got the boat and it has been winterized every fall.

Any one out there have any other things I should check out.

[grizrunner]

Same happened to my friend's Johnson 90. New plugs and ran perfect. Check out another thread here about the Seafoam/marine Stabil comparison. I think Stabil is a better way to go.

[pinkfloyd4ever]

Had that happen to my 99 F50 a couple years back, same symptoms, changed plugs and put 2 gallons gas with one can sea foam and burned the motor around. Either that recipe worked or it needed new plugs, but has been good since

[BPBOB]

I had a 140 Johnson 4 stroke ?2005 that started sputtering and running rough-took it in (Warranty time)and the dealer changed plugs-never a problem after that.

[Fisherman45]

Thanks everyone I am on my way to get new plugs so I can take it out this weekend.

[Northlander]

Replace the fuel filter too while your at it.

[Fisherman45]

Thanks again after 4 new plugs and a new fuel filter the motor is purring like a kitten again.

[Northlander]

Glad it was that simple. Enjoy!