No spark out of cdi unit

[bmoncus]

I have a 115 yamaha v4 with no spark from the cdi unit to the rt 2 cylinders. I have swap coils & plugs. The lt cylinders work fine. I have used a simple timing light to conferm my diagnostic. So before I go & spend 300.00 for a new cdi unit, any suggestion. Yes it is igintion & not carbration,etc. THANKS
Billy

 

[99yam40]

Re: No spark out of cdi unit

Test the inputs to the cdi like your service manual says

 

[bmoncus]

Re: No spark out of cdi unit

If I had a service manual I would have no need to post a question here. Can you elaborate? THANKS Billy

 

[99yam40]

Re: No spark out of cdi unit

I do not have a manual for your motor either, but if I owned that motor and wanted to work on it I would get my hands on a manual. It will save you tons of time and money.There are places to get manuals online if you look

You will need a DVA adapter along with a volt meter or even better a peak reading volt meter made to take the readings on these ignition systems like the manuals state

 

[skrillz78]

Re: No spark out of cdi unit

If you only have spark to all but #2 cylinder you may need a new crank position sensor.I had the same issue on a 1999 60hp Yammy.Crank position sensor controls fire @ #2.sometimes a pice of metal shaving can ruin these.It is a magnet that reads the teeth on a flywheel telling your cdi when to fire.hope this works for you.I'm no mechanic but on mine i replaced that and it worked.

 

[rodbolt]

Re: No spark out of cdi unit

the 115 does not have a crank position sensor, it does have two pulser coils that control two cylinders each . either you do have a rare CDI failure or you have a rare pulser coil failure.
only way to verify which failed is using pulser coil outputs and CDI primary outputs.
only way to verify them is loaded using the correct test equipment AND a service manual.
that or start chunking parts at it.

 

[bmoncus]

Re: No spark out of cdi unit

OK, I have a manuel now & have made the proper tests. Heres what I found, the pulser coils ohm out at 315.5 ohms, that is in spec. The pulser coils test under load & running, 2.5 volts at 1500-1800 rpms & 5.5 volts at 3500-4000 rpms. The igntion coils ohm out at 4400 uhms & that is also to spec. SOOO is it time to price a CDI unit? THANKS Billy

 

[rodbolt]

Re: No spark out of cdi unit

I would also double check the charge coils.
not only for output but for shorts to ground.
then it may be time to price that CDI.
its a two wire coil, open it and the circuit is dead,short 1 leg and voltage is not only reduced but you only get 1/2 of the sine wave its supposed to have.

 

[bmoncus]

Re: No spark out of cdi unit

Thanks for the input. I went back to storage today & checked the charge coils for short to ground & resistance, as i could not start the boat in dry storage. Resistance is in spec & they are not grounded. I found cdi units online for 270-480 bucks at 3 different web sites. I looked at the wiring circuits & can not see any thing else to test. Sooo any one got 2 cents to add before I JUMP.Thanks Billy

 

[seahorse5]

Re: No spark out of cdi unit

You did disconnect the "kill wire" to make sure nothing in the rest of the wiring is affecting the ignition system, right?

 

[99yam40]

Re: No spark out of cdi unit

I would see what the cranking peak voltages are from the charge coils and the cdi output voltages are .
It can be done without starting motor by pulling plug wires off the plugs and attaching them to a spark board. That way they are loaded but not sparking the plugs in the motor while you crank it over. If you have good voltage in but bad voltag out then I would be looking for a CDI