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I have a Yamaha 1989 30SF tiller steer motor and recently I started having this problem. I crank up the motor and go to WOT and the boat will plane off and a few seconds after it plains the motor will start sputering. Sort of a loud popping sound and it will keep doing it until i shut down the motor and when i restart it will be fine again until a few seconds after i plane off and it will repeat... Once it starts the boat will go probably around 5 mph...The only way to get it to stop is to restart the motor.... Its prob about 15 seconds total from crank til it starts to sputter... I replaced the plugs and that didnt fix it.. A buddy said it could be a power pack? Anyone know?
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I would start by checking the compression, check the spark at the same time.
you can make a spark tester,its not hard.
google, homemade spark tester.
then I would look at the fuel system,including the fuel pump.
after that your going to need a peak reading type multimeter or a DVA adapter for a digital multimeter to check the ign system.
also post if this is a 2 or 3 cylinder 30. -
It is a 3 cylinderComment
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the loud popping sound maybe a lean sneeze.
as Rodbolt said look at fuel pump and also sucking air into fuel supply.
compression, spark, and timing have to be good for motor to run properly and are easy to test. then it is up to the proper fuel/air ratio.
Will it idle all day long but just not turn higher RPM?Comment
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I had an old mechanic look at it and he says its probably the fuel pump diaphragm. He said that cylinder 2 controls the fuel pump so we pulled the plug out and turned the motor over and it was shooting out fuel. He said that the diaphragm was letting too much fuel by and fowling out #2... Does this make sense?Comment
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Sounds sorta right, if it's a bad fuel pump diaphragm it's easy to repair or replace, and that would cause your problems. Is that cylinder pretty juiced up with excess fuel? New pump's only about $45! Good Luck!Comment
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