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Thread: 2003 Yamaha 75 hp

  1. #1

    Default 2003 Yamaha 75 hp

    My engine is making a light coughing noise when at idol or engaged slightly while transiting threw the harbor. Once I apply the throttle to half or full power it runs fine. It has been doing this since I first bought the boat 2 years ago. It is a 4 stroke yamaha 2003 75hp. I would guess about 500 to 600 hours on the engine. New plugs and wires. Any suggestions on what it might the cause of the noise?

  2. #2


    if it is backfiring at low speed, the idle jet is probably set too lean. might be set from the factory, or prior owner for a different altitude. have the local shop rejet it for your altitude.
    Last edited by dayooper; 05-26-2011 at 07:14. Reason: gotta learn to spell!


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