How to Check Out CDI on 1997 Yamaha 80hp

[pstephens46]

That sounds fun. Probably gets its ground eventually through an unwilling person! Then you know.

[cpostis]

That sounds fun. Probably gets its ground eventually through an unwilling person! Then you know.

All kind of weird things can happen, just check this out

https://www.youtube.com/watch?v=CXhfkuK9KaM

[99yam40]

Now, even though rarely occurs, an unwanted shunt (where the path of the electrical circuit goes other than where intended and does not short to ground, nor blow fuses and burn conductors or components) is another story.

Had this happen a few times with control circuits for building HVAC systems during my career.

Maybe we can discuss that?

I did finda wiring connector/plug on an old 35HP johnson I had leaking to ground and other wires in the harness some years back. The rubber became conductive.
ended up rewiring the motor myself eliminating the connectors instead of buying a new harness.

took me awhile to figure out why that motor would die and not restart when it got rained on and a little water ended up under the cowling.
Bad enough to be caught out in the bay in a rain shower, but when it shuts down the motor it is real bad.
*****ing motor got me back one time , the next time I just kept playing with the wiring until it fired back up . the hunt was on after that

[fishfun83]

Well. As my luck goes, it is not firing on cylinder 2 when I checked it out for the last time before putting the ole boat in the water. I have NO idea what changed from 2 days ago when it was working. Today I checked the grounds as best as I could as the sun was setting. Tomorrow is a new day and I will take all of your recommendations and start implementing them. I have an analog volt meter coming tomorrow so I can start checking the CDI if necessary.

[fishfun83]

Checked out all of the ground connections to the engine and checked the integrity of as many wires as I could yesterday. Still missing on cylinder 2. Received the analog volt meter in the mail but it did not work. Had to send it back and buy anther one. My luck, so, now I will be waiting another couple days to check out the CDI.

[fishfun83]

more than likely it was not a short, but a bad connection(high resistance) in one of the connectors

How in the world do I identify a high resistance connection when I can not get to the ends of the wires? As an example, wires go directly from the CPS to the connector and then directly to the CDI with no terminals.

[fishfun83]

never good to poke holes in insulation.
they make adapters to hook into the wiring harness so you can get to the connectors.


If you unplug the connectors you can do the unloaded test, but if you want to do the loaded testing with it all hooked up then you can back probe the connectors where the wires run up into the rubber plugs without damaging the wire insulation with small straight pins or paper clips being careful and hook meter up to them

OK. Now that I read this more carefully it makes sense. That will be my project today while I am waiting on my analog volt meter. Will ESPECIALLY pay attention the the connector for the CPS.

[cpostis]

OK. Now that I read this more carefully it makes sense. That will be my project today while I am waiting on my analog volt meter. Will ESPECIALLY pay attention the the connector for the CPS.

You are going to need to read "peak voltage".

Just to be sure, nowhere in this thread do you mention "Analog multimeter with peak reading capability".

Please confirm you are getting this!

Maybe post a link and/or make model meter you have ordered.

Seeing that you had, didn't have, had again, and now don't,; I still think you have a bad connection.

Maybe you want to try using this:

Lisle 20610 - Spark Tester | O'Reilly Auto Parts


Place the spark tester in line to your # 2 spark plug (between the spark plug lead and the spark plug).
Fire your engine up
While engine is running, observe if you have spark or not.
If not, wiggle, pull, push, twist various leads and connectors in you ignition system wiring and see if spark is restored (even intermittently). You may be able to pin point a bad connection. I would concentrate on the wire from the CDI to the # 2 cylinder ignition coil and the 2 wires from your CPS to your CDI. Check that ground lead form your # 2 coil to ground as well.

Good luck!

[fishfun83]

You are going to need to read "peak voltage".

Just to be sure, nowhere in this thread do you mention "Analog multimeter with peak reading capability".

Please confirm you are getting this!

Maybe post a link and/or make model meter you have ordered.

Seeing that you had, didn't have, had again, and now don't,; I still think you have a bad connection.

Maybe you want to try using this:

Lisle 20610 - Spark Tester | O'Reilly Auto Parts


Place the spark tester in line to your # 2 spark plug (between the spark plug lead and the spark plug).
Fire your engine up
While engine is running, observe if you have spark or not.
If not, wiggle, pull, push, twist various leads and connectors in you ignition system wiring and see if spark is restored (even intermittently). You may be able to pin point a bad connection. I would concentrate on the wire from the CDI to the # 2 cylinder ignition coil and the 2 wires from your CPS to your CDI. Check that ground lead form your # 2 coil to ground as well.

Good luck!

The analog voltage meter I purchased was to measure resistance at the various points identified in the Yamaha Service Manual. Yamaha specifically said that a DVM would not work and an Analog Meter was required. I did purchase spark plug tester and have been using that to identify if I have a spark or not. I also purchased a DVA Direct Voltage Peak Reading Adaptor which I will be using to identify voltage using my DVM.

Also, in my Yamaha Manual, there is no mention of measuring voltage and it gives no values. What it does is to tell you to use a YU-91022-B (Yamaha Tester). When you get the switches and knobs turned to the specified placement on the tester, if the component is good, a red light will come on. Sounds to me like they are measuring voltage.

[cpostis]

The analog voltage meter I purchased was to measure resistance at the various points identified in the Yamaha Service Manual. Yamaha specifically said that a DVM would not work and an Analog Meter was required. I did purchase spark plug tester and have been using that to identify if I have a spark or not. I also purchased a DVA Direct Voltage Peak Reading Adaptor which I will be using to identify voltage using my DVM.

Also, in my Yamaha Manual, there is no mention of measuring voltage and it gives no values. What it does is to tell you to use a YU-91022-B (Yamaha Tester). When you get the switches and knobs turned to the specified placement on the tester, if the component is good, a red light will come on. Sounds to me like they are measuring voltage.

A DVM is a digital volt meter, it measures voltage only. A DMM is a digital multi-meter, it measures voltage, resistance, and depending on the particular meter, other values (amperage, hertz, etc.). A DMM can measure peak voltage with a DVA. SOME DMMs have peak voltage measuring capability built in.
In some certain instances an analog meter may be better for measuring, say capacitance.

Measuring peak voltage is basic in diagnosing any CDI ignition system. Now, Yamaha may not have published the specs for peak voltage in your manual for your motor, but they should have.

Still say you have a bad connection. Be persistant looking for it.

[fishfun83]

Thanks cpostis. Last night I decided to check the voltage between the CDI and the coil on number 2 cylinder. Got it all hooked up and number 2 was firing like nothing was wrong. I pulled on wires all over the engine and could not get number 2 to fail. I unplugged connectors, wiggled connectors, twisted connectors, tapped on the CDI itself, and did everything I could think of to get number 2 to stop firing but the engine continued to work like a charm. I did this for about 20 minutes with the engine running.

If the engine is firing on number 2 today, I plan to unbolt the CDI and pull it away from the engine and start moving it around to see if one of the wires leaving the CDI is causing the short. Other than pull and tug and twist and inspect wiring, I don't know what else to do.

Have you ever heard of a case where the CDI is going bad and would work intermittently? I am not ready to give into that theory yet but it is in the back of my mind.

[rodbolt17]

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.

[fishfun83]

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.

When the engine is running, I am getting 200+ volts at the coil when testing as you suggest. At other times when it is missing on cylinder 2, there is no spark. I do not believe this is a fuel issue.

I have switched coils from 1 to 2 and from 2 to 1 and 3 to 2 and the results are the same. When not running right, there is no spark on cylinder #2 but great spark on #1 and #3. I would think that would rule out a bad coil.

I have replaced the CPS. That is not the issue.

I am continuing to look for bad connections or frayed wires. Have been unsuccessful.

One thing I don't understand though. Last night, when the engine was running great and firing on all cylinders, I disconnected the CPS at the connector that runs between the CPS and the CDI. The engine died immediately. With the CPS still disconnected, I was able to restart the engine but had no spark on #2. This I don't understand but probably has no bearing on my problem.

[99yam40]

when #2 is missing does the input to #2 coil still read 200V?

[fishfun83]

when #2 is missing does the input to #2 coil still read 200V?

True to form, this morning the engine is NOT firing on cylinder #2. Measured voltage as I did yesterday at the coil. Voltage was 0.8 volts.