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Ignition diagnosis

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PhilSch

Regular Contributor
I am a newbie when i comes to diagnosing marine engine ignitions. 1994 48 spl has good spark on top cyl but no spark on bottom. The CDI troubleshooting guide says to test the resistance and DVA outputs of the Stator and Timer Base. The DVA tests were in spec but the resistance between the Brown and Brown/Yellow wire was 825 OHMS, nearly double the spec of 450-550 OHMs. Does this mean the stator is bad?
 
The same stator coil is used to fire both cylinders. So rationality says if it fires one, it should also fire the other one. What do you call "good" spark?
 
It jumps a 7/16" gap on the spark tester. The spark looks like it might be a bit thready but I did it outside in daylight.
 
PhilSch said:
View attachment 26607 I just looked in the factory manual. The spec listed by CDI is WRONG. The factory manual says resistance between those wires should be 800-1000 OHMs.
Click to expand...

That bring up an interesting point. Resistance specs are not written in stone. Aftermarket replacement coils, and even OEM mfr's might use a different wire gauge and/or a different number of turns or length and arrive at the same resulting output.
 
CDI electronics have often supplied replacement components with parameters well outside OEM units.....but they work just fine. You can see the difference in many of the tables included in their diagnostic manual.
 
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