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Spark Issue - PLEASE HELP!!

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  • Spark Issue - PLEASE HELP!!

    2000 Yamaha 90HP 2 Stroke C90TLRY

    I have been chasing a spark issue around for weeks.

    - removed plugs, holding one plug attached to boot and touching the engine I only get 2 seconds of spark while cranking and then spark stops but engine is still trying to turn over
    - when CDI is put into emergency bypass, it sparks fine
    - when crankshaft position sensor is unplugged, it sparks fine

    What I've done:
    - tested resistance and voltage with the following components unplugged (using a peak voltage meter): pulsor coil, stator, and crankshaft position sensor
    - pulsar coil and stator passed per yamaha manual specs for "open"
    - crankshaft position sensor did not pass the voltage test - spec if 5.5v min and got 4.79v
    - replaced CPS with brand new one from and still same problem - new CPS shows 5.2V open - still out of spec?
    - swapped CDI with used CDI that owner swears works - same problem - he gladly took it back
    - tried brand new hardness and switch - same problem

    Going nuts here. I feel like the fact that the motor sparks fine when the crank pos. sensor is disconnect and or when CDI is in bypass mode should point to something. I thought it was a bad CPS especially since it tested low but even the new part tests low and does the same thing.

    For the love of God someone please give me some guidance!!

  • #2
    CDI emergency bypass??