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Frank
Frank, Small Engine Tech
Category: Small Engine
Satisfied Customers: 60
Experience:  I've been a small engine technician for 10+ years. EETC Certified.
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I've been trouble-shooting a run problem on my Kohler ch18s

Customer Question

I've been trouble-shooting a run problem on my Kohler ch18s in my Cub Cadet. Runs better at higher throttle settings, but rough at idle and loads up soot in the exhaust. Smokes and belches smoke like crazy and runs rough at idle, however, when I shut off the ignition it smooths out and consistently for 15-30 seconds before it quits from fuel starvation. I've chased down all the electrical components I can, put in new plugs and even reversed them to rule that out, have also rebuilt the carb. I pulled the flywheel shroud to check to see if a coil wire was shorting out but nothing there. The one plug wire seemed pinched suggesting a short at lower engine RPMs, so I inserted a pin in the wire before the abrasion and checked continuity to the plug cap, but got almost zero resistance at 1k. Can this be an ignition module problem?
Will
Submitted: 1 year ago.
Category: Small Engine
Expert:  Frank replied 1 year ago.
Hello,
I'm confused at "When I shut off the ignition it smooths out and consistently for 15-30 seconds before it quits from fuel starvation."
I'm assuming instead of ignition, you mean fuel valve?
Sounds like it's running really rich. The amount of smoke you're saying, I'm wondering if it's a head gasket leak around the valves. OR piston ring blow by in the cylinder, causing oil to enter combustion stroke and burn oil.
If you have a compression tester I'd definitely check If not, might need to pull the head and check for cylinder scoring and gasket leaks.
Check the air filter, make sure it's clean. Check the oil, smell for gasoline, oil height (not overfilled) and color/texture of oil.