My Petrol Lawnmowers pull cord will not pull out of the starter assembly

If the pull cord on your petrol lawnmower is stuck or will not pull out, this is usually caused by either engine resistance, a mechanical blockage, or a fault within the starter system.

This guide covers the most common causes and the steps you can take to resolve the issue.

Table of Contents

1. Freeing the Engine from the Compression Stroke
2. Checking the Engine Oil Level
3. Clearing the Underside of the Deck
4. Checking Cable Tension
5. Inspecting the Self-Propel Drive Belt

Common Causes of a Stuck Pull Cord

The pull cord may become difficult or impossible to pull due to:

• Engine compression resistance
• Incorrect oil level (too low or too high)
• Blockages under the mower deck
• Incorrect cable tension affecting the engine brake
• A slipped or damaged drive belt
• Failure of the recoil starter mechanism

1. Freeing the Engine from the Compression Stroke

Tools Required

• Spark plug tool
• Protective gloves

If the engine stops in the compression stroke, the piston may resist movement, making the pull cord extremely difficult to operate.

Step 1 – Remove the Spark Plug Cap

Disconnect the thick black spark plug lead from the spark plug.

Step 2 – Remove the Spark Plug

Using a spark plug tool, carefully unscrew the spark plug anti-clockwise and remove it from the engine.

Step 3 – Release Engine Pressure

With protective gloves fitted:

1. Hold the engine brake/start lever on the handle.
2. Carefully rotate the blade by hand 4–5 times.

This helps release internal pressure and free the engine.

Step 4 – Reassemble

1. Reinstall the spark plug by hand to avoid cross-threading.
2. Tighten using the spark plug tool.
3. Refit the spark plug cap until it clicks into place.

You should now find the pull cord operates more freely.

2. Checking the Engine Oil Level

Incorrect oil levels can affect engine movement and starting.

Low Oil Level

If there is insufficient oil:

• Add the correct oil type (usually SAE 30 or as specified in your manual)
• Check the dipstick to ensure the level is between minimum and maximum marks
• Gently rotate the blade to confirm the engine moves freely

Overfilled Oil (Hydro-Lock Condition)

If too much oil has been added or the mower has been tipped, oil may enter the cylinder and prevent compression.

To resolve this:

1. Remove the spark plug cap.
2. Remove the spark plug.
3. Pull the starter cord several times to expel excess oil.
4. Clean and refit the spark plug.
5. Reinstall the spark plug cap.

3. Clearing the Underside of the Deck

Blockages beneath the mower can prevent the blade from rotating, which also prevents the engine from turning.

Check for:

• Thick grass build-up
• Twigs or debris
• Obstructions around the blade area

Clean thoroughly before attempting to start again.

Important: Always ensure the spark plug cap is removed before inspecting or cleaning underneath the mower.

4. Checking Cable Tension

If the stop/start (engine brake) cable is too loose, the brake may not fully disengage.

This can increase resistance when pulling the starter cord.

Ensure the cable is correctly adjusted according to your model’s starting or cable tension guide.

5. Inspecting the Self-Propel Drive Belt

If the drive belt has slipped or become misaligned, it may create resistance within the crank system.

Check that:

• The belt is correctly seated on the pulleys
• It is not damaged or stretched
• It has not slipped off the drive system

If necessary, refit the belt following the drive belt replacement instructions.