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2003 Yamaha 70hp 2stroke issue

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  • 2003 Yamaha 70hp 2stroke issue

    hey yall thanks in advance, i currently have a 2003 Yamaha 70hp outboard in the shop, came in for poor running condition, unit would start and idle rough, when advancing the throttle in neutral or under load it would not advance. found fuel ties missing leaking fuel lines, corrected all those issues and still have the issue, we replaced the cdi push to open box, and restarted the unit still has the same issue but if you remove the two yellow wires connected together coming from the cdi push to open box the motor sounds alot better but still not right but will throttle up. Appreciate any and all recommendations and insight.
    Parts that where replaced.
    Spark plugs.
    Cdi
    Carbs gone through and rebuilt with all new gaskets
    fuel lines and fuel ties.
    Compression #1 120psi #2 120psi #3 115psi
    Cylinders have some scarring but nothing terrible. walls still have cross hatching,

  • #2
    I would check to see what the timing is doing.
    Is it in spec and advancing as it should?

    did you check peak voltages into and out of the CDI to make sure they meet minimum spec.?

    if it has good compression and spark, and that spark is at the correct time, you are left with fuel to air ratio problem.
    too much or too little fuel with the air
    either one is a problem

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