'99 Evinrude 4 stroke running rough!!!

[deadduk]

Help Please!!!! I have a 1999 Evinrude 4 stroke 9.9 hp motor that will run great for about 10-15 minutes then it will start to spudder and run really rough and then it will quit. Wait 5 minutes and it will start and run fine for a minute or two and quit again. I have changed the plugs, checked to see that the breather vent is open on the tank, and ran Sea foam through it. Anyone with similar troubles who has advice would be much appreciated.
Thanks Again--DUK

 

[tashasdaddy]

Re: '99 Evinrude 4 stroke running rough!!!

did you check spark at the time it was messing up. if it were a 2 stroke i would say a coil is getting warm and failing.

 

[darrklim2]

Re: '99 Evinrude 4 stroke running rough!!!

Is it overheating? When it starts running rough try removing plug wires one at a time, if you remove one and it doesn't change the way it is running then you know which one to suspect. If it does change move on to the next one.

Edit. If that doesn't seem to be the problem I would suspect a fuel issue.

 

[deadduk]

Re: '99 Evinrude 4 stroke running rough!!!

Lastnight I cleaned out the carb and the jets. Still ran into the same problem. I sprayed fuel directly into the carb while it was running rough with no sucess. This leads me to believe that it is an ignition issue.
darrklim2--How would I know if the motor is overheating? I seem to have a fair ammount of water pressure coming out of the motor... As far as removing plug wires while running bad, would this determine if there is a bad coil? Any advice is greatly appreciated.
Thanks,
DUK

 

[darrklim2]

Re: '99 Evinrude 4 stroke running rough!!!

I'm not certain if a 4 stroke is the same but I would assume it is. After running it a while put your hand on the heads if you can't leave your fingers there for at least 5-10 seconds it is probably too hot.

Yes, removing the plug wires one at a time is a test to see which cylinder isn't getting proper spark. This can then lead you to suspect that cylinder, which could be plug wires, or the coil, or if the coil tests ok and the wires are ok then the power pack is probably suspect. Powerpacks are expensive so you want to be sure that everything else is guaranteed to be ok before replacing the powerpack.

 

[nntravel1]

Re: '99 Evinrude 4 stroke running rough!!!

How many turns out is your main jet? My 2004 did the same thing and the main carb jet was not out far enough. It came 3 turns out from the factory it runs fine now at 5 full rotations out. When it was cold it would start and run but at full throttle it would bog once in a while, after it warmed up it would not idle or run well at all. Opened the jet at all is well.

 

[riverboatsam]

Re: '99 Evinrude 4 stroke running rough!!!

Are you sure about the breather vent,i have a 1999 9.9 evinrude 4 stroke and it doesnt have a vent. sam