Common Whipper Snipper Problems and How to Fix Them

Nothing derails a Saturday morning lawn session quite like a whipper snipper that won't cooperate. Whether it refuses to start, won't feed line properly, or dies unexpectedly mid-job, equipment problems are frustrating—especially when the grass keeps growing while you troubleshoot.

The good news is that most whipper snipper problems have straightforward solutions you can tackle at home without expensive repairs. This troubleshooting guide covers the most common issues, organised by symptom, with step-by-step fixes for each.

Problem: Trimmer Won't Start (Petrol Models)

A petrol whipper snipper that won't start is the most common complaint, especially after storage. Work through these causes in order:

Cause 1: Stale or Incorrect Fuel

This is the number one culprit. Fuel older than 30 days degrades and can prevent starting.

Solution:

1. Drain all old fuel from the tank
2. Mix fresh fuel with two-stroke oil at the correct ratio (typically 50:1 or 40:1—check your manual)
3. Prime the carburettor by pressing the primer bulb until fuel is visible in it
4. Try starting again

Cause 2: Flooded Engine

Over-priming or repeated failed starts can flood the engine with excess fuel.

Solution:

1. Set the choke to the open/run position
2. Hold the throttle fully open
3. Pull the starter cord repeatedly (10-15 times) to clear excess fuel
4. Wait 5 minutes, then try normal starting procedure

Cause 3: Fouled Spark Plug

A dirty or damaged spark plug won't ignite the fuel-air mixture.

Solution:

1. Remove the spark plug using the correct socket
2. Inspect the electrode—if it's black, oily, or damaged, replace it
3. If lightly fouled, clean with a wire brush and reset the gap (typically 0.5mm)
4. Reinstall and try starting

Cause 4: Clogged Air Filter

A blocked filter restricts airflow and prevents proper combustion.

Solution: Remove the filter and try starting. If it starts, clean or replace the filter.

Problem: Trimmer Won't Start (Battery Models)

Cause 1: Flat Battery

The obvious first check—but sometimes overlooked.

Solution: Fully charge the battery and ensure it clicks securely into place. Check the battery indicator lights.

Cause 2: Battery Contact Issues

Dirty or corroded contacts prevent power transfer.

Solution:

1. Remove the battery
2. Clean the contacts on both battery and trimmer with a dry cloth
3. Check for visible corrosion—clean with a pencil eraser if present
4. Reinstall the battery firmly

Cause 3: Faulty Battery

Lithium-ion batteries degrade over time and eventually fail.

Solution: Test with another battery if available. If the battery charges but the trimmer won't run, or if the battery gets unusually hot, the battery may need replacement.

Problem: Line Won't Feed Properly

Symptom: Line Doesn't Advance When You Bump

Possible causes and solutions:

• Line welded together: Heat from use can fuse the line on the spool. Remove the spool and rewind with fresh line.
• Line wound incorrectly: Overlapping or crossed line causes jams. Rewind following the direction arrows on the spool.
• Line too thick: Using line diameter larger than specified can cause feeding problems. Check your manual for the correct size.
• Worn bump knob: If the bump mechanism is worn, it won't engage properly. Replace the bump knob assembly.

Symptom: Line Feeds Out Too Much

Possible causes and solutions:

• Weak spring: The spring inside the spool housing may be worn or missing. Inspect and replace if necessary.
• Incorrect line size: Line that's too thin doesn't grip properly. Use the specified diameter.
• Worn spool: A damaged spool may not hold the line correctly. Replace the spool.

Problem: Trimmer Bogs Down or Loses Power

Petrol Models

Possible causes:

• Clogged air filter: Restricts airflow, causing the engine to run rich and lose power. Clean or replace.
• Old or incorrect fuel mix: Improper oil ratio causes performance issues. Drain and refill with correct mixture.
• Clogged spark arrestor: The screen in the exhaust can become carbon-blocked. Remove and clean with a wire brush or replace.
• Carburettor issues: May need professional cleaning or adjustment if other causes are ruled out.

Battery Models

• Low battery: Power output decreases as the battery drains. Charge or swap batteries.
• Overheating protection: Some models reduce power to prevent overheating. Let the machine cool for 10 minutes.
• Vegetation too heavy: Trying to cut too much at once overloads the motor. Make lighter passes.

Problem: Excessive Vibration

Unusual vibration is both unpleasant and potentially damaging.

Possible causes and solutions:

• Unbalanced cutting head: Uneven line on each side creates imbalance. Ensure equal line lengths.
• Damaged cutting head: Cracks or breaks cause vibration. Inspect and replace if damaged.
• Loose components: Check all bolts and screws for tightness—especially the cutting head attachment.
• Worn clutch (petrol): Internal wear can cause vibration. Requires professional repair.

Problem: Trimmer Runs But Won't Cut

• No line exposed: Advance the line using the bump feed mechanism.
• Line too short: Replace the spool with fresh line.
• Line too thin: Thin line lacks cutting power. Use the recommended diameter.
• Wrong line type: Some vegetation requires twisted or star-shaped line for effective cutting.

When to Seek Professional Help

Some repairs require professional expertise or special tools:

• Carburettor rebuilding or significant adjustment
• Ignition coil replacement
• Clutch repair or replacement
• Internal engine damage
• Gearbox service (brushcutter models)

If you've worked through the relevant troubleshooting steps without success, or if the repair seems beyond your skill level, take your trimmer to an authorised service centre. Bunnings, Total Tools, and independent mower shops can typically service common brands.

Most whipper snipper problems are preventable with regular maintenance. Clean after each use, service seasonally, use fresh fuel, and store properly—and you'll spend more time trimming and less time troubleshooting.