Why Won’t My Weedeater Start?

Whether it’s the first yard care day of the season or just another day trimming the lawn, it’s never convenient to discover that the weed eater won’t start after running fine all of last year.

How Do I Troubleshoot My Weed Wacker?

It happens to us all, though, so knowing how to troubleshoot your weed wacker yourself can save you time when you’re able to identify and deal with the possible issues.

Your specific model will have care instructions, but all gas weed trimmers have certain components in common that you can become familiar with in case of a non-starter.

Cleaning Your Weed Wacker

The underside and component parts of the weed eater can become dirty from buildup. Plant material, soil, oil, and other particles get trapped in the rotary mechanism and any exposed part of the machine.

Making sure the power source is off, the spark plug is disconnected, and the gas tank is empty, clean the debris off the underside with a brush, and water if necessary, to remove any physical blockages that might be stopping one or another process from happening.

It isn’t a bad idea to clean your weed trimmer every other week to keep it clear. This is true for both gas and cordless models.

The Pull Cord

Pulling the starting rope on a weed wacker engages the gas engine, and as the first step to ignition, it could cause problems to getting the motor started. If you’re having difficulty pulling the cord, it could be from a twist or a jam in the coil, or the recoil mechanism could be worn out.

If it’s just stuck, a few firm tugs and a gentle recoil could get it realigned.

Your Gas Fuel String Trimmer

Gas String Trimmer

When you pull on the starter cord, you expect to hear the click of the spark plug igniting the engine, followed by the whipping of the wire. When you don’t hear these sounds or the machine is sputtering out, it could be due to one of several parts of the weed eater’s engine:

  • The fuel tank
  • The carburetor
  • The air filter
  • The spark plug

The Fuel Tank

A few things could be going on with your fuel tank that keeps the weed wacker from starting. It can be as simple as someone having forgotten to refill it the last time it was used. Make sure you keep cans of fresh fuel and oil on hand to fill up as necessary.

Separated Oil and Gasoline

Many weed eaters have a two-cylinder engine, which only has one chamber for both fuel (for power) and oil (to lubricate the engine).

When the mixture sits for long enough, the oil and gas will separate, as the oil is denser than the gasoline. For the best results, making sure the fuel tank’s contents are blended is as easy as shaking it up a bit before use.

Excess Fuel

Too much fuel in the engine’s tank can also prevent it from starting. Fuel and air are mixed in the carburetor, and with too much liquid, the engine is effectively flooded and unable to start. Pouring some of the fuel out safely into a container might quickly solve the problem.

Faulty Fuel Lines

If there’s enough fuel in the tank, but the machine still isn’t starting, it might not be receiving the right amount of fuel. Checking the trimmer’s fuel lines for cracks, leakage, and stiffness every season will help you stay on top of this maintenance need.

These tubes should be replaced at least every other season.

The Carburetor

The carburetor is the part of the engine where the combustion happens: the fuel is ignited and mixed with air to power the whole engine. This part has its own parts, which can be troubleshot according to your specific model’s manual.

All kinds of weed eaters can get dirty, though, and this is one of the main reasons a motor might not be starting. Be sure to clean the carburetor of buildup from fuel remnant at least once a season to keep the motor in good condition.

The Choke Lever

The choke lever is the valve on the carburetor that “chokes” off the air supply to the engine, which helps get it started. A cool engine doesn’t vaporize fuel as well as a hot one does, so keeping the fuel vapors in the engine as it starts and begins to warm up helps it get going.

If your choke valve is open when you pull the starter cord, close it for ignition, and open it back up after ten seconds after the motor warms.

Air Filters

The air intake component of the weed eater’s engine feeds the necessary oxygen into the carburetor to keep the combustion cycle going.

Air filters keep debris and large particles out of the combustion chamber, but these filters become clogged and must be replaced at least once every year to ensure enough air is being fed to the engine.

Clogged filters can lead to overheating, so consider changing the air filter in the middle and at the end of each season.

Clogged Fuel Filters

Having a clogged fuel filter could also be what’s preventing the engine from getting going. Like an air filter, a fuel filter keeps debris and particles out of the combustion chamber, only letting oil and gasoline pass through.

Over time, buildup will collect on the filter, so these should be changed out regularly. A rule of thumb is to replace them every season and when you change out the fuel lines.

Spark Plugs

A spark plug is the catalyst that ignites the engine’s combustion process. If this isn’t working, the engine won’t run. The plug is a small screw-in piece with a coil and porcelain insulator.

Like all other components, these wear out over time, and it’s recommended to replace them, on average, every 100 hours of use, which equates to roughly every other year.

How To Fix A Spark Plug Problem

Since spark plugs are such an important part of an engine, they’re relatively easy to find and replace. Performing a small routine inspection can give you some clues to know if it’s time to put in a new one:

  • Corrosion or oil buildup might cause dirty spark plugs to stop connecting properly. It’s recommended to use sandpaper, a wire brush, and brake cleaner to remove grime from the plug and extend its life
  • As spark plugs age, the electrodes get burnt and worn out and can give inconsistent power. Check the plug for yellowing on the porcelain or metal for signs of aging and compare it with its expected lifetime
  • Spark plugs usually have a recommended period of use given by the manufacturer on their package. Using this as a guideline can help you be sure to have enough on hand and avoid being left surprised at unexpected spark plug burnouts

Author: Matt Hagens

Hi, I’m Matt the owner of Obsessed Lawn. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Learn more about me and find me on Facebook.