No spark .... Charge coil volts/Ohms readings

[miccor]

Hi I've got a 30hp yam that won't start (no spark)
I tested the voltage from the charge coil (one that powers the CDI) and I was only getting 45 volts from pull starting and 119 Ohm resistance from the charge coil when disconnected ..... The manual says PEAK voltage should be between 175 and 210 volts ..... I can't see the cranking voltage in the manual so I don't know if I should be getting more voltage when cranking out of the charge coil ..... From the manual the Ohms reading from the coil should be between 164 and 210 Ohms but I've got 119 Ohm ....
So should I get more than 45v on pull start cranking ??
Dose this sound like a suspect coil ??
Or Do you know what the minimum voltage that the CDI will run on ??

[rodbolt17]

typically anything below about 60V PEAK wont generate enough primary current to induce a voltage in the ign coil secondary circuits.
most digital volt meters wont read peak voltage.
thats what DVA adapters and dedicated peak reading meters do.
the CDI wont step up voltage,it simply stores the rectified AC in a capacitor aaiting a trigger(pulser coil) signal to discharge the capacitor into the ign coil primary circuit.
what type meter and/or adaptor are you using?

[miccor]

THANKS rodbolt17
I was using a cheap digital meter but I put it back together so I could test the voltage with a old anlogue meter (1960"s I think) and getting about 30-40 volts .... But now I have spark and after cleaning the plugs it did fire once but didn't run ..... The spark looks blue but weak .... and after about 3 hrs and a dead arm I haven't got it to fire again

[rodbolt17]

your meter isnt desinged nor will it read peak voltage, it will read about 70% or slightly less than peak.
the CDI doesnt step up voltage,you may even see a 10V voltage loss through the CDI.
the voltage step up is done in the ign coils.
you may wish to post the model number as there are at least 4 versions of a 30 HP two stroke that were avalible for the US market.

[miccor]

Cheers for that ..... So ok then even at 70% it's still well below the manuals 175 to 210 volts ..... The output from the CDI to the coils is about 4 v which is about what the manual says ..... Now that I've got spark I think the spark looks weak and might be breaking down under load cause of the lack of voltage from the coil ..... Dose that sound right ?? .... The model number of the motor is an Aussie model 6J8 30DM (serial number) X ..... As in my other thread which is asking if anyone knows what year it is ..... The 6J8-85520-00-00 looks like the go for a replacement without knowing the year .... but I'll give it to the bloke we take our AC motors to to get rewound to see if he can do it for me .....
Cheers Mick

[99yam40]

I would recommend picking up a DVA adapter or make one and take the readings again before replacing or trying to repair the one you have. The normal meter just does not get the right voltage reading.
They are simple to make if you can find the parts and the DVA adapters can be bought online if not local.

[rodbolt17]

all wrong.
4v at the CDI output would mean NO spark, NONE.
my advice is either buy the correct test equipment and properly test the system or take it to a trained dealership that has technician certifications on the wall.
not knowing how many cylinders, nor which of the 3 possible ign systems you have thats about all I can say.
other than you have CDI charge coil inputs,CDI trigger(pulser coil) inputs AND CDI outputs to the ign coil primary windings, SEE why you have to properly ID which system we are disscussing and WHICH coil?charge,pulser ign OR lighting.
ALL do very seperate specific functions and the first 3 affect ign.
I dont have access to international market stuff but with some clear pictures I can ID the system.

[99yam40]

Rodbolt, I just notices the B-word under your name over there. Hated to see that, but good to know where you still can be found when needed hopefully
Some times you have to watch out for over medication of the cold ones if that had anything to do with it