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Message Subject: Yamaha 50 4 stroke runs rough?

Jigman

Posted 4/17/2010 12:20 AM (#435685)
Subject: Yamaha 50 4 stroke runs rough?

Posts: 60

I have a yamaha that is hard to start and does not want to idle after it has got warm during the day. It has new plugs and I use ring free every tank. It runs fine first thing in the morning but later in the day I have a tough time with it at idle, it usually dies on me. Ant ideas? Thanks!

VMS

Posted 4/17/2010 7:32 AM (#435704 - in reply to #435685)
Subject: Re: Yamaha 50 4 stroke runs rough?

Posts: 3508

Location: Elk River, Minnesota

Hiya,

Any chance you have a timing light to check timing of the spark plugs? I once had a johnson 50hp that after a trip to canada was off on it's timing. I couldn't keep it running, and when it did, it idled rough. Checked the timing and found it was off a little...once adjusted, that motor barely took a turn of the key and it was firing when warm and purred like a kitten. There are times I miss that motor....it was rock solid!!

So...Just thinking that might be something to check....

It might be just a carb adjustment as well. If you pull the plugs are they wet? If so, it is running a tad rich, or it might just be something as little as an idle screw that needs to be turned up just a touch...

Lots of things to check, so I am pretty much talking "tongue in cheek" here...but hopefully it gets you in a direction that helps improve the situation.

Steve

schoenbm

Posted 4/17/2010 8:54 AM (#435715 - in reply to #435685)
Subject: RE: Yamaha 50 4 stroke runs rough?

I had a similar problem with the same motor. It would run fine sometimes and terrible at others. After some invetigation I found that the ethanol in the gas had completely destroyed the fuel connections on both the tank and motor sides. There is an O-ring in the connection that had essentially dissolved. Replaced the connections and I haven't had a problem since. Cheap fix if its the same problem.

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