How to Check Out CDI on 1997 Yamaha 80hp

[fishfun83]

So here is the latest story.

Last night I cranked the engine up with the spark indicator attached to cylinder #2. Engine was working perfectly. Put the cover on the engine and went to bed. This morning I pump the fuel bulb, and crank it up. NO spark on cylinder #2. I removed the 3 bolts retaining the CDI and moved it around all over the place hoping to find a bad connection. No spark on #2.

I do not believe I have a bad connection. I have pulled and tugged and taken apart and inspected every connector and wire that I can get my hands on. The CPS is brand new. None of the three coils work on cylinder #2 so it is NOT a coil problem.

My question is: Would either the Pulser Coil or the Stator Assembly cause ONLY #2 Cylinder not to fire?

[cpostis]

So here is the latest story.

Last night I cranked the engine up with the spark indicator attached to cylinder #2. Engine was working perfectly. Put the cover on the engine and went to bed. This morning I pump the fuel bulb, and crank it up. NO spark on cylinder #2. I removed the 3 bolts retaining the CDI and moved it around all over the place hoping to find a bad connection. No spark on #2.

I do not believe I have a bad connection. I have pulled and tugged and taken apart and inspected every connector and wire that I can get my hands on. The CPS is brand new. None of the three coils work on cylinder #2 so it is NOT a coil problem.

My question is: Would either the Pulser Coil or the Stator Assembly cause ONLY #2 Cylinder not to fire?

I'm going to have to defer, can't see how it sparks sometimes and sometimes does not. Others will have to help.

Not giving up, just want others to respond.

[fishfun83]

cpostis: I want to try to read the output voltages from my coils. My service manual, as we have discussed before, only gives me resistances. I know my engine uses Yamaha Part no. 6H0-85510-01-00 coil. In one of your manuals, does it give output voltages for that and the pulser coil?

[99yam40]

Right now you know that when you have spark you have 200v to the #2 coil, no spark you have .8v to it.
so now you need to read voltages into the CDI to make sure it is getting the voltage it needs .
bad part is you have no specs, but if you can read when there is spark and when there is no spark on #2 that will tell you if something on the input side is the cause.

you also have 2 other cylinders to take readings on for a comparison on the CDI output

[cpostis]

yall be way over complicating this.
hook up the volt meter to the #2 primary ing coil.
slip the meter lead into the bullet connector sleeve.
the other to ground.
take it out and run it.
if the CDI output voltage remains constant its not a spark issue.
unless it is a failed coil or ign secondary lead.

Rodbolt, this appears to be an intermittent problem (sparks , doesn't spark, sparks again).

In an another thread by this OP you replied
" and that 1 pulser coil controls spark on 1&3. 2 is made up in the CDI based on the CPS input. "

How is # 2 made up in the CDI based on CPS output? The only voltage inputs to the CDI I see are from the pulsar coil and the charge coil.

If # 2 spark is not con*****ed by pulsar coil, and is made up in the CDI, does the CDI input voltage from the charge coil supply the spark voltage to the CDI and spark is initiated by the CPS via the CDI?

I know CDI's don't fail often, but is their a chance it has failed in this case with the intermittent problem? Again, sometimes he has good voltage from the CDI to # 2 coil, sometimes not.

Tough diagnosing intermittent problems!!

I hope I'm not having you to repeat what you have already said, but with the op's symptoms and what he has said, what would you do?

[99yam40]

In my thinking if all inputs into the CDI are good (CPS included) even when the spark goes away on #2

and the voltage out of CDI to #2 coil is good when #2 sparks but then is not when spark goes away, would lead me to think the CDI is bad or a connection internal or external is keeping it from getting the info needed to know when to fire #2.

All you can do is test what you can

[fishfun83]

Thanks again for all of your information. With Thanksgiving upon us, I am going to take what remains in this day and tomorrow as a day to give thanks for what we have. Blessings on you all and your families.

[cpostis]

Thanks again for all of your information. With Thanksgiving upon us, I am going to take what remains in this day and tomorrow as a day to give thanks for what we have. Blessings on you all and your families.

Thank you FF!

Happy Thanksgiving Day to you and yours!!!

[panasonic]

Is it possible that your new cps is bad?

[rodbolt17]

I am suspecting you have the rare CDI failure.
that system uses one charge coil for primary ign.
it uses one pulser coil to control spark base timing on cyl 1&3.
the CPS controls spark on #2 via the CDI.
lose a pulser coil and you will lose spark on 1,3 or both 1and3.
lose a charge coil and you lose spark on all 3.
lose a CPS and you lose spark on #2.

[fishfun83]

Hope everyone had a great Thanksgiving.

I have checked voltages and resistances until I am blue in the face and have come to the 85% conclusion that I am in need of a new CDI. However, there is one loop I want to close.

Checking my stator output voltage while cranking and checking resistance.

Low speed: Service Manual Resistance Read Brown to Red = 220 to 270 ohms
My reading 81 ohms
Service Manual Read Brown to Red Voltage = 100 volts
My reading 67 volts.

High speed: Service Manual Resistance Read Blue to Red = 70 to 90 ohms
My reading 231 ohms
Service Manual Read Blue to Red Voltage = 60 volts
My reading 112 volts.

So if you reverse my readings for the Low Speed and High Speed, my readings are great. Confused as to why they are opposite.

Please offer your opinions.

[rodbolt17]

my guess is a miss print in the manual.
however we know the charge coil is working as you have spark on the other two.

[fishfun83]

Thanks rodbolt 17

CDI replacement it is. Once I get it installed, I will come back to the forum to give all my result.

thanks again to everyone for their assistance.

[99yam40]

I looked back to see if you ever posted what the CPS out put voltage to the CDI ever measured but did not see anything.
Have you made sure the input from CPS is getting to the CDI when #2 does not spark?

[fishfun83]

Just to make sure 99yam40, thinking that the CDI is probably bad anyway, I pushed 2 pins into the wires about 1/4 inch from where they go into the CDI and cranked the engine. The motor was NOT firing on cylinder 2 and I was getting in the neighborhood of 15.7 volts into the CDI from the CPS as measured with my DVM with DVA. Based on what I have seen for CPS output voltage, 15.7 volts seems rather high, but it is a brand new CPS, so, maybe the 15.7 volts is operator error.