Outdoor Power Equipment and Small Engines - Stihl HL100K extended trimmer

with the 4-mix engine. Have a no start condition. Cleaned and rebuilt the carb. The unit is getting plenty of gas so checked for spark. Grounding the plug couldn't detect a spark so finally employed the poor man's method and touched the plug. Detected a shock but it wasn't a strong one like the jolt you get when you accidently touched a spark plug on a car. So I am suspecting the ignition coil may be bad. Hence my question: How do you test the ignition coil. I have a volt meter but I not sure how to perform the test and what should be the reading range for a good/bad ignition coil.

Thanks for the help.

The best is to disconnect the kill wire from the coil & recheck for spark... If still none, than you will need a coil....Make sure the plug is well grounded.. I have a jumper wire made with alligator clips on the ends cus with so much plastic on these little engines sometimes its hard to get a good ground.... Roger

I seem to remember the ignition module on the 4-mix engines have a lifetime warranty. Call a Stihl dealer and ask. You will need to the proof of purchase. If the ignition module is in fact not firing with cutoff switch disconnected you in fact have a defective ignition module.

These ignition modules employ a retard feature that if defective they will spark but the spark is not in sequence with compression stroke and valve closing. Therefore, they will appear to be good and are not.

Send me a PM with email address and I will send you some troubleshooting information for the 4-Mix engine.