Doug Hislop
ArboristSite Lurker
I have a Stihl MS 180 C that starts cold fine, idles fine, revs fine, but cuts off with no spark after 10-20 seconds. It will start back up and run for an indeterminate brief (less than 15 seconds) period and cuts off again with no spark. Once I have repeated this cycle a few times the saw will not crank for a few minutes. Once the saw is left for a few minutes the saw will crank again.
I’m determining no spark with an inline spark test light. When the tester shows spark it cranks and runs correctly. When the tester shows no spark it will not crank or continue to run. Here is what I have done to the saw lately; partly as general maintenance and partly chasing this issue.
1. Fresh fuel (ethanol free, right mix)
2. New fuel filter
3. New fuel line
4. Checked the spark plug and gap. Replaced plug.
5. Removed and cleaned exhaust muffler. The screen had a very small amount of buildup. Cleaned the screen and replaced the muffler.
6. Ran the saw with and without the bar and chain to ensure no weird interference from the chain side.
7. Opened, cleaned, and replaced carburetor. I get the same results with two different carbs.
8. Checked the compression with a very simple starter rope test. The compression feels good. Looking in the exhaust side doesn’t show anything unusual in the cylinder.
9. Inspected flywheel and all electrical wiring. No visible damage or wear.
10. I checked the gap between the flywheel and the coil.
11. Replaced the ignition coil and electrical wiring. I get the same results with the original coil and the new coil.
I most recently figured the ignition coil was the issue, but have now concluded the saw fails the same way with two different coils. I suppose by some astounding coincidence I could have two similarly failing coils, but that seems really farfetched.
Does anyone have some recommended troubleshooting tips I have overlooked?
I’m determining no spark with an inline spark test light. When the tester shows spark it cranks and runs correctly. When the tester shows no spark it will not crank or continue to run. Here is what I have done to the saw lately; partly as general maintenance and partly chasing this issue.
1. Fresh fuel (ethanol free, right mix)
2. New fuel filter
3. New fuel line
4. Checked the spark plug and gap. Replaced plug.
5. Removed and cleaned exhaust muffler. The screen had a very small amount of buildup. Cleaned the screen and replaced the muffler.
6. Ran the saw with and without the bar and chain to ensure no weird interference from the chain side.
7. Opened, cleaned, and replaced carburetor. I get the same results with two different carbs.
8. Checked the compression with a very simple starter rope test. The compression feels good. Looking in the exhaust side doesn’t show anything unusual in the cylinder.
9. Inspected flywheel and all electrical wiring. No visible damage or wear.
10. I checked the gap between the flywheel and the coil.
11. Replaced the ignition coil and electrical wiring. I get the same results with the original coil and the new coil.
I most recently figured the ignition coil was the issue, but have now concluded the saw fails the same way with two different coils. I suppose by some astounding coincidence I could have two similarly failing coils, but that seems really farfetched.
Does anyone have some recommended troubleshooting tips I have overlooked?
