Stihl MS 250 Will Not Idle: How to Fix It

Q: Why does my Stihl MS 250 start but won't idle?

This usually indicates the idle speed is set too low or the low-speed fuel mixture is incorrect. The carburetor's L and LA screws need adjustment, or the carburetor may need cleaning.

Q: What causes a chainsaw carburetor diaphragm to dry out?

Ethanol in modern gasoline, old fuel sitting in the tank, and normal wear over time can cause rubber diaphragms to harden and crack, affecting fuel delivery at idle speeds.

Q: Can I adjust my Stihl MS 250 carburetor myself?

Yes, basic idle and low-speed adjustments can be done by most users with the right tools. However, high-speed adjustments should be done by professionals to avoid engine damage.

Q: How often should I clean my Stihl MS 250 carburetor?

Clean the carburetor annually or whenever you notice idle problems, hesitation during acceleration, or if the saw has sat unused for several months with fuel in the tank.

Abstract

When your Stihl MS 250 chainsaw won't idle properly, it typically indicates the idle speed is adjusted incorrectly or the carburetor diaphragm has dried out. This common issue can usually be fixed by adjusting the carburetor screws or cleaning/replacing carburetor components.