My Petrol Hedge Trimmer will not idle

Quick Answer

If your petrol hedge trimmer starts but stalls when the throttle trigger is released, the most common causes are stale fuel, a blocked air filter, or incorrect carburettor settings. Before adjusting the carburettor, carry out the basic checks below to rule out common issues.

⚠️ Safety Notice

Before carrying out any maintenance or adjustments:

• Work in a well-ventilated area.
• Keep hands and loose clothing away from the cutting blades.
• Wear suitable protective equipment.
• Ensure the hedge trimmer is placed on a stable surface.
• Be aware that incorrect carburettor adjustment can affect engine performance and may cause engine damage.

Why Won't My Hedge Trimmer Idle?

If the engine starts but cuts out when the throttle is released, possible causes include:

• Old or incorrectly mixed fuel
• A blocked or dirty air filter
• Restricted fuel flow
• Incorrect carburettor settings
• General engine wear or maintenance issues

Begin with the simple checks below before considering carburettor adjustment.

Preliminary Checks

Check the Fuel

Ensure the fuel is:

• Fresh
• Correctly mixed according to the manufacturer's recommendations
• Free from contamination

Old or incorrectly mixed fuel can cause poor combustion and unstable idling.

Check the Air Filter

Inspect the air filter and ensure it is clean.

A dirty or blocked air filter can restrict airflow and affect the fuel-to-air mixture, causing the engine to stall at idle.

Replace or clean the air filter if necessary.

Check the Fuel Cap

Ensure the fuel cap is fitted correctly and tightened by hand.

The cap should be secure but not overtightened.

A poorly fitted fuel cap can sometimes affect fuel delivery and engine performance.

Carburettor Adjustment – Low-Speed (L) Screw

If the preliminary checks have been completed and the hedge trimmer still will not idle, the carburettor settings may require adjustment.

Important

⚠️ Carburettor adjustment requires mechanical knowledge and the correct tools.

Incorrect adjustment can:

• Cause poor engine performance
• Prevent the engine from starting
• Lead to engine damage

If you are unsure, contact our Technical Support Team before proceeding.

Tools Required

• Carburettor adjustment tool (Pacman type)

Step 1: Warm Up the Engine

Start the hedge trimmer and allow it to reach normal operating temperature.

Adjustments should always be carried out on a warm engine.

Step 2: Locate the Adjustment Screws

The carburettor has two adjustment screws:

Step 3: Adjust the Low-Speed (L) Screw

Carefully adjust the L screw until:

• The engine idles smoothly.
• The engine no longer stalls when the throttle is released.
• The cutting blades remain stationary at idle.

Make small adjustments and allow the engine time to respond.

Step 4: Adjust the High-Speed (H) Screw

With the throttle fully open:

1. Turn the H screw anti-clockwise until the engine begins to lose maximum RPM.
2. Slowly turn the screw clockwise until the engine reaches full RPM and runs smoothly.

Avoid over-adjusting the high-speed setting.

Step 5: Check Idle Operation

Release the throttle trigger and confirm that:

• The engine returns to a steady idle.
• The engine does not stall.
• The cutting blades remain stationary.

If necessary, make further minor adjustments to achieve a stable idle.

Unable to Perform This Procedure?

If you are not confident carrying out carburettor adjustments, we recommend that you do not proceed.

Attempting to dismantle or adjust components incorrectly may invalidate your warranty and could result in further damage.

Please contact our Technical Support Team for assistance.

Frequently Asked Questions

Why does my hedge trimmer stall when I release the throttle?

This is commonly caused by incorrect carburettor settings, stale fuel, a blocked air filter, or restricted fuel flow.

Should the blades move while the engine is idling?

No. The blades should remain stationary when the engine is idling correctly.

Can old fuel cause idling problems?

Yes. Fuel can deteriorate over time and affect engine performance, making the hedge trimmer difficult to idle or start.

What does the L screw do?

The L (Low Speed) screw controls the fuel mixture at idle and low engine speeds.

Can I adjust the carburettor myself?

Only if you have the correct tools and experience. Incorrect adjustments can worsen performance or damage the engine.