Weed Eater Wont Start? 7 Common Problems and Fixes

ByDavid Holtzman
Weed Eater Won’t Start

Weed eaters, also known as string trimmers or weed whackers, are essential tools for keeping your yard neat and tidy. But like any gas- or battery-powered tool, they can occasionally refuse to start, leaving you frustrated and stuck with overgrown grass.

Whether you’re using a gas-powered, electric, or battery-powered weed eater, there are common reasons they might not start—and just as many solutions. In this comprehensive guide, we’ll break down why your weed eater won’t start and how to fix it yourself, often without needing a mechanic or shop visit.

🔧 Common Reasons Your Weed Eater Won’t Start

Before diving into detailed fixes, here’s a quick look at why your weed eater might be giving you trouble:

For Gas-Powered Weed Eaters:

  1. Old or bad fuel
  2. Clogged carburetor
  3. Fouled or worn spark plug
  4. Dirty air filter
  5. Flooded engine
  6. Bad ignition coil
  7. Blocked fuel lines
  8. Stale primer bulb
  9. Compression issues
  10. Choke or throttle not set properly

For Electric/Battery-Powered Models:

  1. Dead battery or low charge
  2. Damaged power cord
  3. Faulty switch or trigger
  4. Motor failure
  5. Blown fuse or circuit issue

🛠 Step-by-Step Troubleshooting Guide (Gas Models)

✅ 1. Check the Fuel

Old fuel is the #1 cause of starting issues. Gas begins to degrade after 30 days, especially ethanol blends.

Fix:

  • Drain old fuel.
  • Refill with fresh, non-ethanol fuel (or fuel with an added stabilizer like STA-BIL).
  • Use a 40:1 or 50:1 gas/oil mix, depending on your trimmer’s requirement.

✅ 2. Inspect the Spark Plug

A fouled, cracked, or loose spark plug can prevent combustion.

Fix:

  • Remove the spark plug.
  • Check for black soot or corrosion.
  • Clean with a wire brush or replace it (usually a $2–$5 part).
  • Make sure the gap is correct (typically 0.020–0.030 inches).

✅ 3. Clean the Air Filter

A dirty air filter restricts airflow and can choke the engine.

Fix:

  • Remove the air filter cover.
  • Take out the filter and inspect it.
  • Wash a foam filter with soapy water, let it dry, and lightly oil it.
  • Replace a paper filter if clogged or torn.

✅ 4. Prime and Choke Properly

Incorrect starting procedure is a common issue.

Fix:

  • Press the primer bulb 5–6 times until you see fuel enter the bulb.
  • Set choke to “Full” or “Start”.
  • Pull the cord a few times. If it sputters, move to “Half-Choke” and pull again.

✅ 5. Check for a Flooded Engine

Overpriming or multiple failed start attempts can flood the engine.

Fix:

  • Set choke to “Off” or “Run”.
  • Hold throttle wide open.
  • Pull the cord several times until the engine clears out and starts.

✅ 6. Examine the Carburetor

Carburetors get gummed up with old fuel. If cleaning the air and spark system doesn’t help, this is your next stop.

Fix:

  • Spray carburetor cleaner into the air intake.
  • If needed, remove and disassemble the carb, clean all jets and passages.
  • Rebuild kits are available for under $20.

✅ 7. Look at the Fuel Lines

Cracked or hardened fuel lines cause air leaks and prevent proper fuel flow.

Fix:

  • Inspect lines for cracks or discoloration.
  • Replace both fuel and return lines if needed (usually sold in kits).
  • Make sure lines are connected securely to the primer bulb and carb.

✅ 8. Check the Ignition Coil

If your spark plug is good but you’re getting no spark, the ignition coil might be bad.

Fix:

  • Use a spark tester to check for spark.
  • If none, replace the coil (usually under $25–$50).
  • Make sure the coil gap is correct—check manufacturer specs (commonly 0.010–0.014″).

✅ 9. Inspect the Recoil Starter

Sometimes, the issue is mechanical.

Fix:

  • Open the recoil housing.
  • Look for broken springs, tangled rope, or worn pawls.
  • Rebuild or replace the recoil if needed.

✅ 10. Check Engine Compression

Low compression means worn piston rings or a damaged cylinder.

Fix:

  • Use a compression tester. You want at least 90–100 psi.
  • If below that, a rebuild or new engine may be necessary.

🔋 Battery/Electric Weed Eater Not Starting?

✅ 1. Battery Charge

Obvious, but often overlooked.

Fix:

  • Fully charge the battery.
  • Check that the charger is functioning.
  • Try a second battery if available.

✅ 2. Inspect the Trigger and Switch

The safety lock, switch, or trigger could be faulty.

Fix:

  • Clean the switch area.
  • Look for broken internal wiring or a loose trigger spring.
  • Replace the switch assembly if unresponsive.

✅ 3. Check for Obstructions

Sometimes string tangles or debris block motor movement.

Fix:

  • Turn off power.
  • Clean under the head.
  • Manually rotate the head to check for resistance.

✅ 4. Circuit Issues

For corded models, a tripped breaker or blown fuse can stop power flow.

Fix:

  • Reset any GFCI or circuit breaker.
  • Try another outlet.
  • Check for cord damage.

🧹 Preventative Maintenance Tips

To avoid future starting problems, follow these:

  • Use fresh fuel every 30 days or use a stabilizer.
  • Drain the tank if storing more than a month.
  • Clean the air filter every 5–10 hours of use.
  • Replace spark plug annually.
  • Lubricate cables, head, and trigger linkages.
  • Check string head for clogs or wrapped grass.
  • Use OEM parts or reliable aftermarket replacements.

❓ FAQs: Weed Eater Starting Problems

Q1. Why does my weed eater only run for a few seconds then die?

This usually indicates:

  • Dirty carburetor
  • Clogged fuel line
  • Blocked fuel filter
  • Bad ignition coil

Q2. Can I use car fuel in a 2-cycle weed eater?

Only if it’s mixed with 2-cycle oil at the correct ratio. Straight car gas will destroy the engine.

Q3. How do I know if my engine is flooded?

Strong gas smell, wet spark plug, or no fire even with good spark = flooded engine.

Q4. Is it better to use ethanol-free gas?

Yes. Ethanol attracts moisture and leads to corrosion and gumming in carburetors.

Q5. What does it mean if the pull cord is stuck?

It could mean:

  • Seized engine
  • Rope tangled in recoil
  • Grass jammed in the shaft or clutch

🧠 Final Thoughts

When your weed eater won’t start, the fix is usually something simple: old gas, a dirty spark plug, or improper choke usage. By systematically checking fuel, spark, air, and compression, you can often bring your trimmer back to life without spending much money.

Whether gas-powered or electric, routine maintenance and correct operation will go a long way in preventing frustrating start-up issues.

Would you like a PDF version of this guide or a printable troubleshooting checklist to keep in your garage or tool shed?