Symptoms
- Engine stalls whenever the throttle is released
- Runs fine only at higher RPM
- Rough, uneven idle before stalling
- Needs choke to stay running at idle
Likely causes
- CommonClogged idle circuit in the carburetorSmall idle jets clog easily with varnish from old fuel.
- CommonIdle speed screw set too lowA simple adjustment issue rather than a clog.
- PossibleDirty air filter affecting idle mixtureRestricted air throws off the idle fuel-air ratio.
- PossibleVacuum or gasket leakA leak affects idle more than higher throttle settings.
What to do
- Check and clean or replace the air filter first.
- Locate the idle speed adjustment screw (usually near the throttle linkage) and adjust per the manual to raise idle slightly.
- If adjustment doesn't help, the idle circuit in the carburetor likely needs cleaning with carburetor cleaner spray.
- Check all visible gaskets and hose connections near the carburetor for leaks.
- Run fresh fuel through the system if the current fuel is more than a month or two old.
- Retest idle stability after each adjustment before moving to the next step.
- If idle issues persist after cleaning and adjustment, a small-engine shop can rebuild the carburetor.
Tools and parts
- Small flathead screwdriver
- Carburetor cleaner spray
Carburetor rebuild kitSearch: “small engine carburetor rebuild kit”
When to call a pro
A small-engine shop can clean or rebuild the idle circuit if basic adjustment doesn't stop the stalling.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.