I have an old tiller with a Kohler single-cylinder 4-stroke engine. It
lost all power (over about 30 secs), and now won't start. Since then,
- Replaced spark plug. (Which does spark, when grounded to the
- Points look OK.
- Compression looks OK (75 psi).
- Cylinder is getting fuel (plug gets wet, and exhaust smells.)
- Carb float valve works, and float seems OK.
- Coil resistances look OK.
- I cranked it in the dark, and didn't see or hear anything bad
around the coil.
I suspect that I have a weak spark when the plug is installed. But, a
new coil costs $75, which is a kind of expensive experiment.
To test the coil, I made a 10:1 voltage divider (with a HV 10M
resistor), and looked at the spark plug voltage with a scope. With the
plug not grounded, I see a 4-6KV pulse. When the plug is grounded, this
drops to about 1KV. I get the same 1KV when the plug is in the cylinder
- Is above consistent with a 'weak' coil?
- Is there another way to test that?
And, any other thoughts would be appreciated.