Symptoms
- Engine fires immediately then dies within a few seconds
- Runs only with choke partially on
- Dies as soon as throttle is applied
- Repeated stalling on restart
Likely causes
- CommonClogged fuel filter or fuel lineA blocked filter lets just enough fuel through to start but not sustain running.
- CommonDirty carburetor jetsVarnish from old fuel restricts the idle circuit.
- PossibleClogged air filterRestricted air makes the mixture too rich to keep running.
- PossibleCracked fuel lines or primer bulbAir leaks into the fuel system disrupt the mixture.
- Less commonBad spark arrestor screenA clogged muffler screen chokes the engine after it warms up.
What to do
- Drain old fuel and refill with fresh 2-stroke mix at the correct ratio.
- Inspect the clear fuel line and filter inside the tank for dark, gummy buildup and replace if dirty.
- Clean or replace the air filter.
- Check fuel lines and the primer bulb for cracks by looking for fuel leaks or an underfilled primer bulb.
- Try starting with the choke fully off if the engine was already warm; using choke on a warm engine floods it and causes stalling.
- If it still dies, adjust the idle screw slightly higher if the model has one, and try again.
- If problems persist, the carburetor likely needs professional cleaning or rebuilding.
Tools and parts
- Fresh fuel mix
- Small flathead screwdriver
- Replacement fuel filter
In-tank fuel filterSearch: “trimmer fuel filter replacement”
Fuel line kitSearch: “small engine fuel line tubing”
When to call a pro
If cleaning the fuel filter and air filter doesn't help, a small-engine shop can clean or rebuild the carburetor.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.