Tested Resistances

dnale

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Jun 11, 2003
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Location
South Lyon, Michigan
I finally found the portion of the manual where it kinda guides you through testing your electrical system. Stator resistance ok, pickup ok, key switch ok, tors ok'd.

I came across the ignition coil being off. I'm going to see about getting one tomorrow. The primary coil is supposed to be .2ohms +/- 20% @ 68*F. I tested it multiple times and came up with 0.8 ohms. Obviously that's over the +20%. The secondary coil reading came up ok. My ground was continuous. I also had out of limits when I tested my spark plug caps. They are supposed to be 5k ohms. I'll check on those too.

Has anyone else ever had these just go bad?
 
I have had bad spark plug caps before makes the sled run real goofy, like a fouled plug with backfiring.
 
Your coil may be ok. It really depends how accurate your Ohm meter is and how good your leads are. Unless you have a 0 ohm adjust on your meter you could be off by 0.5 ohm.
 
If you have a pic or a diagram showing which parts you want checked I'll dig them out of the shed and check mine for you. They're from a 98. Don't know if they're different from your 96 parts, but would give you an idea.
 
resistor caps have a resistor in them. I believe this is what goes bad. I believe they are used to cut down electrical interference. I had them go bad on a Jet Ski.. It was a pain trouble shooting.
 
Yes I have had bad spark plug caps - seems they are either good or way ot of the 5K ohms range. Mine were in the Meg ohm range.

My three coils are still original and they are slightly out of range and I bought some used ones from a TY member and they measured about the same as mine, I ran both sets without a diference so I just put mine back on.

Tod
 
I picked up new ngk's this weekend. I just put a new string on my starter so I"ll try it tomorrow. The ngk's test ok so if I have any luck, maybe that's what it is.
 
dnale said:
How does something with no moving parts go bad though?

Corrosion - can cause a high resistance or open circuit.

Vibration - can cause the same by causing a wire to crack or break - or cause the insulation to wear through which creates a short.

Temperature cycles - same as vibration.

Old age - break down of insulation.

The coils on newer motors are more dependable but I have replaced dozens of bad coils on all different kinds of engines.
 
Electricity takes the shortest (least resistance) path to ground regardless of what material it is. Just lean on the engine and grab a spark plug boot to test this. It is no respecter of persons or things.

Electric parts fail or work improperly all the time. due to many causes including the ones listed above.
 
They were likely open (too much resistance) or shorted (too little). Too much and the spark can't make the jump, too little and it can jump through the plug ahead of the electrodes. In either case the tip of the plug doesn't spark.

For example: One of the plugs on an old tractor quits sparking, I pull the plug wire off and loosely place the boot back on which leaves the actual connection about 1/4 inch or so apart. The cylinder starts firing again.

Here is the quiz: Who can tell me why this would make the plug start sparking again?

Sorry no budget for prizes . . .
 


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