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Yamaha 9.9 won't start when cold

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  • Yamaha 9.9 won't start when cold

    I just purchased this used motor and it will not start when cold. I cleaned out the carb. I have to use my thumb as a choke until it warms up. Once it warms up the crankcase vacuum switch open up, the plunger on the top of the carb goes down and it idles and runs fine. How does the carb choke when cold?? I think this funcion is inop or plugged. Model F9.9LG, Code 6G9Lser. 302277Any help would be great!!!Thanks

  • #2
    Re: Yamaha 9.9 won't start when cold

    Howdy, FLE.I agree that the start-enrichment system isn't working correctly. Three bi-metallic vacuum switching valves sense temperature of the block and the ambient air and operate the starter plunger to enrich for starting.You said you have to use your thumb as a choke. Does that mean that you are restricting the air flow or that you are operating the "emergency knob" on top of the carb? The "emergency knob" is located under a plastic cover on top of the carb. With the starter plunger "UP" an extra passage is opened that allows an enriched mixture into the manifold.If your plunger is UP when cold, and drops down when warm, that part is working correctly. The passages may be plugged.Check this out. Be very careful not to seperate the plunger from the diaphram it is hooked to.Good luck. You will be very smart to get a manual before you tear into the carb.Red sky at night. . .JB


    • #3
      Re: Yamaha 9.9 won't start when cold

      Thank you for the quick reply. I was using my thumb to restrict the air to force a choke. the piston is up when cold and goes down when it has warmed up. Its's in the up position that there is no richness coming for the passage it is suppose to be coming from. I'll have to let the carb soak and hope what is ever blocking the passage becomes free. Ill have to thank the guy that stored the motor without draining the carb.I'll let you know how I make out.Again,Thanks for the help.