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Bought a 90 Yamaha 2 stroke back in March. Removed oil injection and installed new style tiller handle. Had been running the motor just fine on the back of my new boat until recently. One day I took it to the ramp and it had difficulty starting. Finally got it started and but it wouodnt stay running. Took the boat home. Completely Rebuilt all 3 carbs. Problem persists. Replaced stator. Problem persists. Spark test shows weak fire on all 3 cylinders. Busted out the multimeter with the peak voltage adapter. Results recorded in attached picture. Really getting frustrated. Need help. Thanks in advance
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I cannot open the attachment.
what were the voltage numbers for charge coil out put?
what were the numbers for CDI output ?? -
I can open it - but I can't read the OP's writing....
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looks like some below minimum going in to CDI and no readings of what is coming outComment
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ok
what that spec shows is someone does not understand what CDI means.
it means it is a CAPACITOR DISCHAGE IGNITION.
means we use chage coils to simply chage a capacitor.
a cap is kinda like a very quick discharge battery.
the charge coils simply provide an A/C voltage.
the cap passes the A/C yet stores it as a DC voltage.
once charged it must be discharged before charging again.
this is why you MUST test the charge source both loaded and unloaded.
all the trigger does is send a trigger or a gate signal to an SCR.
the SCR is a simple electronic device that once triggered will not shut off until a low current threshold is met.
but the CDI box will not amplify anything.
it may drop a few volts from input to output but it mostly outputs about the input.Comment
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The stator results were above the minimum recommended CDI supplied specifications. Everything meet minimum specs except for :
White/red trigger to ground wire with 1.8v (2.5 minimum)
White/green trigger to ground wire with 0.0v
Brown stator to blue stator resulted in below spec 78v and 54v on the second test (85v minimum)
Brown stator to engine ground resulted in below spec 77v and 53v on the second test .
About to replace the trigger tomorrow. Thanks.Comment
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