fluctuation

  1. dkerphunter

    Yanmar 3GM30F engine RPMs fluctuate when engine warm

    Hi, I have a 1985 3GM30F installed in a Hunter 336. It's been perfect for 21 years. This year, the RPMs have started to fluctuate. When the engine's cold and for the first 20 minutes of operation, it behaves normally. After about 20 minutes at cruise speed around 2,500 RPMs, RPMs fluctuate down...
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