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  1. 09-17-2019, 11:45 AM #1
    techman
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    2003 Yamaha 0x66 fuel injected. strange problem

    I have this motor on a 2003 champion 193. when I take off it will run right up to about 60 and no further. if I let of the gas a couple times and punch it back down its like it found a new gear and I can hit 68 mph. does this about 50% of the time. any guesses?
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  2. ClarkBird
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    #2 09-17-2019, 01:23 PM
    check your TPS
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  3. techman
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    #3 09-17-2019, 01:31 PM
    i have .5v at idle and 4.05 at wot
    Last edited by techman; 09-17-2019 at 03:47 PM.
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  4. ClarkBird
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    #4 09-17-2019, 03:22 PM
    5V - How are you measuring? There is a specific procedure to check. You should see anywhere from .48v - .6v at idle.
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  5. techman
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    #5 09-17-2019, 03:47 PM
    sorry.. should have said .5v at idle
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  6. 21XDC
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    #6 09-17-2019, 04:13 PM
    I'm guessing fuel delivery is the problem...

    Marks Props 317-398-9294, 1850 East 225 South, Shelbyville, Indiana 46176 propellerman59@gmail.com http://www.marksprops.com/index.html
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  7. TwinStick
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    #7 09-17-2019, 04:59 PM
    Mine was doing something very similar. I trouble shot for a long time. Mine ended up needing new plugs.
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  8. techman
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    #8 09-17-2019, 07:57 PM
    i have new plugs and cables
    checking vst filter tomorrow too. hoping I can find one local. looks easy to replace
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  9. techman
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    #9 09-17-2019, 08:03 PM
    me too.. when it's running good it does pretty well. about 68 mph at 5800 rpm. about 500 rpm and 8 mph less when it's not.
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  10. allstock
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    #10 09-19-2019, 07:48 AM
    Sounds like its going into failsafe. Mine was the knock sensor but any electrical issue can cause that.
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  11. techman
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    #11 09-19-2019, 05:57 PM
    Thanks for all the input. cleaning the o2 sensor took care of it. smoother idle and smoking less at idle and picked up another 3 miles an hour.
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