Weed Eater Won’t Start – Top 10 Reasons and Guide

With a weed eater, the task of keeping your garden neat and trim should be a simple one. Unfortunately, sometimes even the best of plans can go awry, especially when our trusty equipment gives up the ghost. If your weed eater gives you trouble this Spring don’t just give up and take it to your nearest repair outlet.

Weed eaters are fairly simple machines. With a little advice and some forethought, you shouldn’t find it too difficult to pinpoint the cause of the fault. If you know what to look for, you can quickly have your machine up and running again, saving yourself time and money.


If yours is a gas-driven weed eater, you could have a problem with the fuel feed.

First, check the fuel tank to make sure that there is fuel in it. If the fuel is too low, your weed eater may not start.

Put fuel in the tank and try starting it again.

If it still won’t start you should change the oil if it is more than 90 days old. Older than this and the fuel becomes thick and sluggish.

In this condition, it won’t flow into the carburetor properly and you’ll starve the engine of fuel.

Air Filter

If your weed eater is struggling to start it may be starved of oxygen. Check your air filter to see if it is clean or otherwise clogged up with dirt. If it is dirty, you can tap it on a flat surface to remove any loose debris and dirt.

Alternatively, you may have to replace it with a new one to get your weed eater in good health again.

Fuel Filter

Likewise, a dirty fuel filter might prevent fuel from getting through into the carburetor, but it is not common for fuel filters to clog up. If this is the case with yours replacing it should get your trimmer up and running again.

Spark Plug

Carbon and oil can build up on spark plugs and cause a problem.

If your weed eater is showing no sign of life it may have a faulty or dirty spark plug. Try cleaning the spark plug with a wire brush and a little bit of gasoline.

Removing the dirt may bring your weed eater back to life. If this doesn’t work you may have to replace the old spark plug with a new one.

When you have the spark plug out, check the ceramic area for cracks. If there are cracks in the ceramic it is time to change it.

Also, check the gap between the nodules. It should measure anything between 0.25” to 0.30”. Anything more or less will give you problems.


The carburetor is that part of the weed eater that sprays the fuel around the engine to keep it going. It’s the heart of the machine and if it isn’t well, you’re going to have problems getting your weed eater going.

Sometimes the primer bulb upon which the carburetor is located is the culprit and replacing it might get your machine going again.

When gasoline breaks down it forms all kinds of gums and resins and these can block the little jets in the carburetor. This will prevent the fuel from flowing into the combustion chamber and igniting.

Simply cleaning the carburetor might be enough to get your whacker going again. To do this take out the air filter and spray carburetor cleaner into the intake. Leave the chemical in the carburetor for a few minutes to dissolve the residues. Put the filter back and try to start the weed eater again.

If you see that there are cracks or breakages in the carburetor it is worth replacing the entire carburetor rather than the weed eater as carburetors are relatively inexpensive.

Electrical or Battery

If your electrical weed eater fails to start, you sometimes need to start with the most obvious causes.

Check that the cord is plugged in and that the electricity is switched on.

If it is battery operated weed eater do a similar check on the charging station and check that the charger is still fully functional. Make sure that the weed eater switch is in the on position.

Very often extension leads can fail with time. Try swapping out the extension lead in case it’s faulty. Also, make sure that the circuit breaker and fuse are both in working order.

Spark-Arrestor Screen

Some trimmers have a little screen over the exhaust. It’s a safety feature intended to prevent fires.

From time to time this screen may get covered in carbon. Because it impedes the exhaust, the weed eater will lose power and if the build-up is bad enough your trimmer may not even start.

Clean the screen with an industrial cleaner or replace it completely.

Low-Quality Oil

Low-quality oil causes carbon emissions that will lead to sluggish performance and could damage your trimmer over time.

Change to high-quality two-stroke oil that burns cleanly.

Flooded Engine

Many of us, in our frustration, will keep trying to start the troublesome weed eater.

If you’ve done this you may have flooded the engine. If this is the case set the machine on its side. Put the choke lever on run and pull the start cord to burn off the excess fuel.

Leaving your trimmer to rest for a short while may help to resolve the problem.

Improper Venting of the Gas Tank Cap

The gas tank cap has a venting hole that helps air into the tank to replace the displaced gasoline. If the hole is blocked the flow of fuel may become sluggish and your weed eater won’t start. Check the hole and clean it to return your weed eater to its old form.

Best Practices to Prevent a Weed Eater from Not Starting

  • Mix gas and oil according to the instructions
  • Clean or replace filters regularly
  • Clean or replace spark plugs every season
  • Clean or replace the carburetor if necessary
  • Drain gas when weed eater not used for longer period
  • For Electric weed eaters: check electrical cords, fuses, extension cables, and power sockets

To avoid problems when you pull your trimmer out after a long winter of hibernation, it is best to clean and prepare your machine for storage.

In doing this when Spring arrives you can haul it out, fill it with fresh fuel and start the job. You’ll save yourself the frustration of battling to get your weed eater going when all you want to do is neaten up the garden.