Yamaha 4-stroke running ROUGH (simple fix)

today we dive in to find the culprit of a outboard running really crappy, and the outcome really surprised me personally but was super simple and maybe simple fix for your boat motor as well

[KarlWatling]

Thanks. Sent me in the right direction. Boat had been sitting for 6 months. Had ethanol free fuel. Had fuel issue in the past and fixed with replacing fuel and new filters. Didn't work this time, turned out to be plugs. It acted the same as the fuel issue from the past.

[shadyfieldhomestead]

I just recently changed out my timing belt and got my Yamaha 115 in perfect timing. When I started it I noticed a slight clicking coming from the fuel rail and I thought to myself, was that there before. Everyone else told me that fuel injectors can make noise just not a loud noise. Anyway, I heard your engine running at the end of the video and I heard it in yours and it was the exact same noise and level of loudness as well. I used a stethoscope on the fuel rail and realized it was just those fuel injectors making some noise. Can’t even hear it on the starboard side of the engine just if you’re up close to the port side where the fuel rail is.

[rickcross]

Seen this a few times. Especially on engines that run poor quality fuel and never get used to their potential. Carbon building up and smashing the plug

[fishin-impossible]

I Am The Captain. Good info Adam. Glad you found your problem.

[John-pccx]

My 115 had the same thing, not firing right. That bottom spark plug was rough and had not been replaced in four seasons. Replaced them all and it runs fine. Looks like some grease got into the plug wire

[martyprice]

Just for info, The ground goes out on that model. [eventually] The ground wire goes to the painted block. To assure you don't get caught on the water with no power, remove the ground wire, sand off the paint from the block and reinstall. If, the housing breaks out on the side of the block, as it can when steel bolts mate in aluminum, don't fret. Notice the hole already there to run a through bolt and nut. Apparently, they moved the wire to not crowd the filter but left the original set up. Paddling is no fun. But hopefully I saved someone the trouble

[mattorrell]

So I removed all four of my spark plugs they all had fuel on them. First time boat owner only took the boat out once and it has an alarm going off. It won’t go above
2000 RPM.

[jerryoxendine]

I started having a problem at full throttle RPM won't get over 4, 000