My responses in Blue:

Test results blow in red bold (I'm not yelling):

Measure the AC Ignition power pin voltage in the wiring harness (at the CDI connector) to ground while cranking. It should measure 80 volts AC or so: 36 volts

This is really low, but maybe good enough to make spark. I know that 45 volts AC is high enough. This voltage is directly proportional to cranking speed (and affected by other stuff as well). Is your starter cranking a little slow?

Measure the Timing Trigger pin voltage in the wiring harness to ground while cranking. This should measure 0.2 to 0.5 volts AC.: 0 volts

This isn't right. You should measure something here beside zero volts. Make sure you have the meter set on AC volts and set to the lowest possible scale. What is your lowest scale, BTW? If it is 200 volts full scale then maybe your meter just isn't accurate enough to measure 0.2 volts AC.

The resistance to ground isn't right either. Zero ohms to ground indicates a short (and that would give you zero volts while cranking too), but too many other things are also wrong with all the other measurements. Therefore I suspect issues with the meter or the measurement technique. Is it possible that you're measuring the wrong pin? Remember that when looking into the connector the pinout is mirror imaged from the picture of the CDI (since you have to flip the connector over to plug it in).

With the engine stopped measure the AC Ignition Power pin resistance (in ohms) to ground. Ignition switch and/or kill switch settings don't matter for this test. It should read 450 ohms or so. 0 with switch on and off

This is not right. If it really is zero ohms then this line is shorted to ground and you won't get spark. But if this line is shorted then you would also get zero volts for the AC ignition power voltage test. You got 36 volts. These two results conflict with one another. Make sure you have the ohmmeter set to the lowest scale that doesn't cause an overscale reading, make sure you have the right pin, and repeat this test. Also make sure you get repeatable numbers. If the measured values are changing then you are not measuring it correctly, have a bad connection at one or both probes, or have a bad meter.

With the engine stopped measure the Timing Trigger pin resistance to ground. Once again the ignition/kill switch settings don't matter for this test. It should measure 150 ohms or so. 0 with switch on and off

See the above comments and repeat this test

*_CDI and Ignition Coil Continuity Tests:_*
Measure the resistance of the ground pin in the wiring harness at the CDI connector to ground. It should read zero ohms. 4.2 ohms

This isn't right. Let's check the meter. Short the two leads together with the meter set to the lowest ohms scale. Does it read zero, or something else? Also make sure your probe connections are making good contact. Dig the probes into the quad frame and connector pin. You should always read the same value. If it varies you have a bad connection or your meter is flakey.

Measure the resistance of the Ignition Coil pin in the wiring harness at the CDI connector to ground. 3.3 ohms

This is way high. Again I think there are too many suspect readings to think they are all problems with the quad.

Pull off the spark plug wire and measure the resistance of the spark plug wire to ground: Open curcuit

Lets check you meter again. Take a wet kitchen sponge and sprinkle it lightly with salt. Stick your probe into the sponge about a inch apart from one another. You should meaure something in the kilo ohm range (something like 6K ohms or 20K ohms). The actual value you read depends on moisture and salt content, how far apart the probes are in the sponge, and the surface area of the probes in contact with the sponge. Once you have you meter measuring many K ohms correctly then remeasure your ignition coil secondary to ground. Be sure to select a scale that allows you to see several kilo ohms (like 200K ohms full scale).

Be sure to wash the salt off your probes so they don't corrode.

What the heck

I still haven't written up the rest of the tests, but I will do that soon. I think the above issues have to be resolved first before moving forward.

 

Lynn,

Thank you so much for your efforts.

I will do what you suggest. This is the meter I am using.

FLUKE 7-300 automatic selection:
V AC 4-300
V DC 4-300
Ohms 0-400

It doesn't have any means to select, it does it by itself. If I must purchase a new meter for this application, what do you recommend?

Dave

 

Fluke meters are top of the line. Unless there is some overwhelming reason to suspect the meter is broken I would stick with the Fluke. Auto ranging is nice too. I wish my meter(s) had that. (Actually my meter at work does have that, and it is a Fluke). Try repeating the tests. Strive for repeatability and accuracy. Things such as the AC power pin measuring 36 volts AC in one test, and shorted to ground in another test cannot both be true.

Some more tests (after the previous issues are behind us):

All tests up till now had the CDI disconnected. Now it is time to plug it back in. With the CDI installed, ignition on, all kill switches off, and cranking the engine:

1) What is the DC voltage on the CDI kill switch pin?
2) What is the AC voltage on the CDI kill switch pin?

The above voltages will not be the same.

3) Measure voltage on the ignition coil pin on the CDI connector while cranking the engine. Note: This test is really problematic, and in the past I've advocated not doing it. However others have convinced me it is worthwhile doing as long as it is recognized that it may give erroneous results depending on what meter is used. The voltage on the ignition coil primary is usually very short pulses of high voltage and high frequency energy. It usually goes 150 volts negative first, then rings back and forth plus and minus, at a rate of 30,000 times per second, and damping out to zero within a few cycles. This happens infrequently (and briefly) compared to the rest of the time where the voltage sits at zero. Meters aren't designed to measure this. Different meter designs measure differently. On top of that there is more than one CDI design out there, so the waveform here is not a given. So if you have the most common CDI design, and the most common meter design, this is what you should see:

You should get a series of readings that look like this: zero, zero, zero, 39 volts, zero, 67 volts, zero, zero, zero, 10 volts, 22 volts, zero.... etcetera. The order and value of the readings of course are random. What is happening is that the meter is taking a snapshot of the voltage and reporting it. Most of the time it gets zero volts, but occasionally it gets a hit on the actual coil drive voltage which could be anywhere from 0 to 150 volts. If you see this sequence then it means you igniton coil is getting driven. That means you have a CDI with a high voltage supply at least partially working, and it is being triggered by the pickup coil. That is an important piece of info. It is a data point that can be used to analyze the overall problem.

On the other hand if you get something completely different then it may be CDI design, meter design, measurement error, etcetera. Not much of a data point in this case.

 

Lynn,

I resurrected an old Simpson analog multimeter I had put away when I got the Fluke. It has a much lower ohms threshold. I redid the tests the best I know how and the results are below. Now I remember why I bought the Fluke.

Measure the AC Ignition power pin voltage in the wiring harness (at the CDI connector) to ground while cranking. It should measure 80 volts AC or so: 36 volts, stock battery (I used a larger battery to increase the cranking speed and only found 38 volts as a result)

Measure the Timing Trigger pin voltage in the wiring harness to ground while cranking. This should measure 0.2 to 0.5 volts AC.: 0.1 volts

With the engine stopped measure the AC Ignition Power pin resistance (in ohms) to ground. Ignition switch and/or kill switch settings don't matter for this test. It should read 450 ohms or so. 550

With the engine stopped measure the Timing Trigger pin resistance to ground. Once again the ignition/kill switch settings don't matter for this test. It should measure 150 ohms or so. 125

*_CDI and Ignition Coil Continuity Tests:_*
Measure the resistance of the ground pin in the wiring harness at the CDI connector to ground. It should read zero ohms. 0 ohms

Measure the resistance of the Ignition Coil pin in the wiring harness at the CDI connector to ground. 3 ohms

Pull off the spark plug wire and measure the resistance of the spark plug wire to ground: 5500 ohms


I will perform to next series of tests this evening after work.

Have a great day.
Dave

 

Lynn,

I took it upon myself to go ahead with the next series of test you asked for. I am not sure if you have had the time to review my last post, but here are the last readings:

Some more tests (after the previous issues are behind us):

All tests up till now had the CDI disconnected. Now it is time to plug it back in. With the CDI installed, ignition on, all kill switches off, and cranking the engine:

1) What is the DC voltage on the CDI kill switch pin? 20 vdc
2) What is the AC voltage on the CDI kill switch pin? 15 vac

The above voltages will not be the same.

3) Measure voltage on the ignition coil pin on the CDI connector while cranking the engine. 90 to 103 (meter not fast enough I guess, but that was the extreems I got)

Dave

 

The readings in the last email seem believable. The 36 volts AC (ignition power) is lower than most but I think it should still work. The Trigger voltage is lower than most, but it may be the meter response to a very non-standard waveform. Plus, in this post you are measuring voltage spikes at the coil primary which says the CDI must be firing. I have no idea what an old analog Simpson will do with fast voltages spikes, but the fact that substantial voltages are being measured at the coil primary is significant.

The Kill Switch pin voltages are believable based on the low AC power voltage.

I would double check all the voltages in the tests one more time to see if they are still the same (maybe you've already done this). Then if you still have no spark I would change the coil and spark plug.

 

Thank you so much for your help.

I have double and triple checked these values with matching results. I am going to order the Coil today.

I'll let you know how it works out.
Dave

 

Lynn,

I wanted to let you know that the coil solved the problem. I installed it and she fired right up.

You have made my boy VERY HAPPY. I can't thank you enough for your time and effort. Folks like yourself are hero's. I can only hope I will somehow, someday be able to return the favor.

Dave

 

Dave,

You're welcome.

I'm very glad you got it working.

 

Nice work, Lynn.

Congratulations, Dave.
[I know how those "happy boy" moments make you feel]