Fix Husqvarna Weed Eaters That Won't Start, Idle or Feed Line
To restring a Husqvarna trimmer, cut 15-20 feet of .095” line, remove the bump head by turning counterclockwise, wind the line in the direction of the arrow on the spool and feed both ends through the eyelets. Common Husqvarna trimmer problems include hard starting (fix: fresh 50:1 fuel mix), trimmer line not advancing (fix: clean bump head, replace spring) and engine dying at full throttle (fix: replace fuel filter, $5-10). The popular 128LD is a 28cc, 11.1 lb homeowner model.
Models Overview
Gas Trimmers
| Model | Engine | Weight | Use |
|---|---|---|---|
| 122C | 22cc | 8.4 lbs | Light homeowner |
| 128LD | 28cc | 11.1 lbs | Homeowner multi-tool |
| 324L | 25cc | 10.1 lbs | Prosumer |
| 525LS | 25cc | 10.8 lbs | Professional |
| 535LS | 34cc | 12.1 lbs | Commercial |
Engine features:
- Two-stroke (50:1 mix required)
- Smart Start system (low effort starting)
- Air Injection (centrifugal air cleaning)
Battery Trimmers
| Model | Battery | Weight | Use |
|---|---|---|---|
| 115iL | 40V (BLi10) | 7.1 lbs | Homeowner |
| 320iL | 40V (BLi200) | 9.5 lbs | Prosumer |
| 520iLX | 36V (BLi200) | 10.6 lbs | Professional |
| 535iRXT | 36V (BLi300) | 13.6 lbs | Commercial |
[NEED REAL IMAGE: Husqvarna trimmer models]
Won’t Start Fixes
Won’t Start
Check first:
- Fresh 50:1 fuel (under 30 days old)
- Fuel valve open (if equipped)
- Choke in correct position
- Kill switch in RUN position
- Primer bulb pumped
Quick test: Spray starting fluid into carburetor.
- Fires briefly = fuel delivery problem
- Nothing = spark or compression issue
Smart Start Procedure
Husqvarna’s Smart Start reduces pull force. Follow this sequence:
Cold start:
- Prime bulb 6-8 times (until fuel visible)
- Set choke to FULL (closed)
- Pull cord until engine fires (may not run)
- Move choke to HALF
- Pull until engine runs
- Move choke to RUN when warm
Warm start:
- Choke OFF
- Pull - should start in 1-2 pulls
Flooded Engine
Strong fuel smell indicates flooding.
Recovery:
- Remove spark plug
- Pull cord 10+ times to clear cylinder
- Wait 10 minutes
- Install fresh or dried plug
- Start with choke OFF, throttle FULL
- Pull until fires
Hard Starting - Common Causes
Fuel-related:
- Old fuel (over 30 days)
- Wrong mix ratio
- Clogged fuel filter
- Cracked fuel lines
Ignition:
- Fouled spark plug
- Failed ignition module
- Kill switch shorted
Air:
- Dirty air filter
- Clogged spark arrestor
Starts Then Dies
Dies immediately:
- Choke stuck closed
- Air leak at carburetor gasket
- Fuel not reaching carburetor
Dies after 10-30 seconds:
- Tank vent blocked (creates vacuum)
- Fuel filter clogged
- Carburetor needs cleaning
Dies when throttle applied:
- High-speed jet clogged
- Fuel delivery restricted
- Spark arrestor blocked
See our string trimmer won’t start guide for detailed troubleshooting.
[NEED REAL IMAGE: Husqvarna trimmer starting]
Running Problems
Bogs at Full Throttle
Causes:
- Fuel filter clogged (most common)
- Spark arrestor blocked
- High-speed mixture too lean
- Air filter dirty
- Exhaust port carbon buildup
Diagnosis order:
- Check air filter - clean or replace
- Remove and clean spark arrestor screen
- Replace fuel filter
- Clean carburetor high-speed circuit
- Adjust H screw (if accessible)
Poor Idle
Symptoms:
- Stalls at idle
- Idle too low
- Head keeps spinning at idle
Causes:
- Idle screw adjustment
- Low-speed mixture off
- Air leak at crankshaft seals
- Dirty carburetor
Idle adjustment: Turn idle screw (T) clockwise to raise RPM. Head should stop at idle.
Engine Surges
RPM fluctuates up and down repeatedly.
Causes:
- Partial carburetor blockage
- Air leak at gaskets or seals
- Fuel delivery inconsistent
- Diaphragm wear in carburetor
Fix: Clean carburetor thoroughly. Replace diaphragms and gaskets if worn.
Loss of Power
Check:
- Air filter condition
- Spark plug gap and condition
- Fuel freshness
- Exhaust/spark arrestor blockage
- Compression
Fuel System Problems
Fuel Mix Requirements
All gas Husqvarna trimmers require 50:1 mix.
| Mix | Oil per Gallon |
|---|---|
| 50:1 | 2.6 oz (76 ml) |
Use quality 2-stroke oil. Husqvarna HP or XP oil recommended but any quality 2-stroke oil works.
Fuel tips:
- Use 89+ octane ethanol-free when possible
- Mix only what you’ll use in 30 days
- Add stabilizer if storing longer
- Never use E15 or higher ethanol
For fuel issues, see our small engine fuel problems guide.
Fuel Lines
Husqvarna trimmers have fuel pickup lines that deteriorate from ethanol exposure.
Replace when:
- Hard starting after sitting
- Won’t prime
- Visible cracks
- Every 2-3 years as maintenance
Line configuration:
- Pickup line goes to bottom of tank (weighted filter)
- Return line (if equipped) shorter
See our fuel line replacement guide.
Carburetor Service
Husqvarna uses Zama carburetors on most models.
When to service:
- Won’t start after fuel system work
- Runs poorly after cleaning attempts
- Surging or inconsistent RPM
- High hours without service
Basic service:
- Remove air filter assembly
- Disconnect fuel lines (note positions!)
- Remove carburetor mounting bolts
- Spray cleaner through all passages
- Replace diaphragms and gaskets
- Reassemble and adjust
See our Zama carburetor repair guide.
[NEED REAL IMAGE: Husqvarna carburetor]
Head Problems
Line Won’t Feed
Causes:
- Line tangled inside spool
- Wrong line diameter
- Bump knob worn
- Spring broken or weak
Fix:
- Remove head cover
- Clear any tangles
- Verify correct line size (.080-.095” typical)
- Replace worn bump mechanism
T35 Head Loading
The T35 is Husqvarna’s standard bump-feed head.
Loading procedure:
- Remove bump knob (counterclockwise)
- Remove spool
- Wind line evenly in direction of arrows
- Leave 6” tails
- Thread through guides
- Replace spool and knob
Line capacity: Approximately 25 feet of .095” line
Head Won’t Spin
Causes:
- Clutch failure
- Drive shaft broken
- Head jammed
- Gearbox failure (attachment models)
Check: Disconnect head and verify shaft spins when engine revved.
Battery Model Problems
Won’t Power On
Check:
- Battery fully charged
- Battery seated correctly (push until click)
- Safety trigger engaged
- Error lights flashing?
If no response:
- Remove and reseat battery
- Clean contacts
- Try different battery
- Check for visible damage
Short Runtime
Expected runtime varies by model and load:
| Model | Light Use | Heavy Use |
|---|---|---|
| 115iL (2.0Ah) | 20-30 min | 10-15 min |
| 320iL (4.0Ah) | 40-60 min | 20-30 min |
| 520iLX (5.2Ah) | 50-70 min | 30-40 min |
Improve runtime:
- Keep battery warm before use
- Don’t run at full throttle constantly
- Trim grass, don’t fight thick brush
Motor Issues
Symptoms:
- Motor won’t spin
- Weak power
- Overheating
Solutions:
- Check for debris jamming head
- Let motor cool if overheated
- Motor failure usually requires professional service
Maintenance Schedule
Every Tank (Gas Models)
- Check air filter
- Verify fuel line condition
- Check trimmer head
Every 25 Hours
- Clean air filter thoroughly
- Inspect spark plug
- Check fuel filter
- Lubricate gearbox (if equipped)
Every 50 Hours
- Replace spark plug
- Replace fuel filter
- Replace air filter
- Check clutch operation
Annually
- Replace fuel lines
- Clean/service carburetor
- Check clutch and drum
- Inspect all fasteners
- Clean cooling fins
Storage
End of season:
- Run fuel out or add stabilizer and run 5 minutes
- Remove spark plug, add small amount of oil to cylinder, pull cord slowly
- Clean entire trimmer
- Store in dry location. See our storage guide for more tips.
Related Guides
- String Trimmer Won’t Start
- Stihl Trimmer Problems
- Echo Trimmer Problems
- Zama Carburetor Repair
- Fuel Line Replacement
- Small Engine Fuel Problems
Summary
Husqvarna trimmers are reliable machines when maintained properly. Most problems trace back to the fuel system - old fuel gums up carburetors quickly. Use fresh 50:1 mix and replace fuel lines every 2-3 years. The Smart Start system makes these trimmers easy to start when everything is working correctly. Battery models offer convenience with less maintenance but different troubleshooting needs.