Motor Running Rough

[kcman]

The last two times I have taken the boat out I have noticed that the motor runs very rough at start up and continues to run rough (with absolutely no power) for the first 5-10 mins then eventually smooths out. Even after running for a while, if I stop the engine and start it back up, it repeats the rough running for the first 5-10 mins. In addition, if I slow it down to idle speed, it will revert back to the rough running again. I have called the dealer but it will be a while before they can get out. In the meantime, I am open to any ideas on solving the problem (I changed out the fuel water separator at the beginning of the season). Someone mentioned to me that the fuel vent may be clogged but I have no idea of where it may be to check. Appreciate any ideas. Thanks.

 

[cwag911]

Have you tried any Seafoam or injector cleaner. I put it in every can of fuel I buy.

 

[kcman]

I have not but that is a good idea. I just checked and I have a 1/2 can in my basement. I was opened two years ago but I assume it is still good since it was stored in a cool dry location. Will put it in the boat this afternoon and see if that helps.

 

[cwag911]

Forgot to ask, what motor do you have?

 

[kcman]

I have a Yamaha 25hp. I just got back from the boat -- added sea foam and ran it for over an hour. Also changed the fuel filter and fuel water separator and then took it for a test drive and it is still running rough. Basically when it is in gear, it will not go over about 2500 RPM's but when I disengage the gear, it will rev up all the way and runs smooth. Very confusing for me at this point.

 

[SEMPERFI8387]

I have a Yamaha 25hp. I just got back from the boat -- added sea foam and ran it for over an hour. Also changed the fuel filter and fuel water separator and then took it for a test drive and it is still running rough. Basically when it is in gear, it will not go over about 2500 RPM's but when I disengage the gear, it will rev up all the way and runs smooth. Very confusing for me at this point.

I have a 2017 with 20hp. First out this season had same thing. Dealer changed needle and seat as it was sticking. They said at mechanics update meeting it was brought up that these have been having issues. Mine would run fine in neutral. Put in gear, it would stall. He rebuilt my carb right at the dock. Maybe an hours work.