Yamaha 50hp CDi

[daleburt]

Hi
I have a 1987 Yamaha 50hp 3 cyl. I'm only getting a spark to the top plug.
I've tried 3 sets of plugs and still only get top cylinder.
I've tested the HT coils and all three are working.I've tested the pulsar coils and they are between 340-358ohms,which the manual tells me is fine.The charge coil is reading 225ohms,the manual says that's ok. I can't seem to get any resistance readings from the CDi unit.
Is this a CDI problem or could there be another reason for the fault??

 

[robert graham]

Re: Yamaha 50hp CDi

Maybe exchange plug wires and caps to isolate a bad wire/cap?

 

[daleburt]

Re: Yamaha 50hp CDi

I did that.I connected each of them,in turn, to the #1 cylinder.They all sparked well in #1 but I got nothing out of #2 & 3.
I swapped around all 3 plugs,same result.all 3 HT coils,same result.Swapped pulsar coil leads and still got the same result.No spark from #2-3 but bright blue spark from #1
The only thing I cant test properly is the CDi

 

[robert graham]

Re: Yamaha 50hp CDi

Are the plugs very wet with fuel?

 

[daleburt]

Re: Yamaha 50hp CDi

Yes,plenty fuel just no spark.
I connected a strobe light to each HT cable to confirm the lack of current.

 

[99yam40]

Re: Yamaha 50hp CDi

Do you have a manual for your motor? My 1999 C40 says to check the peak voltage out puts from the CDI, Charge coils and Pulser coils for trouble shooting not just ohms. This require a peak reading voltmeter or a adapter.

 

[daleburt]

Re: Yamaha 50hp CDi

I have a manual but there are no peak voltage setting for the 87.
I have borrowed a CDi unit so I'm going to try it soon.

 

[daleburt]

Re: Yamaha 50hp CDi

It's definitely the CDi. I put the borrowed 1 onto my engine and it ran perfectly.Put my 1 on my friends engine and got the same problem as my engine.
New CDi unit