Petrol Strimmer Starts But Cuts out When Revved

If your petrol strimmer starts but cuts when revved, then you should check some of its internal parts. Here, we will discuss how you can identify the fault and repair it. Check the user’s manual of your trimmer to know the accurate instructions according to its make and model.


Responsible to mix fuel and oxygen, a carburettor is an important part of the combustion process. You can find this component under the air filter. You have to fine-tune the carburettor because as it can increase the problems if adjusted poorly.

Remove if there is any cover on the carburettor. Take out the filter and air cleaner cap. Check if any obstructions can block airflow. Find the adjustment screws and back out both the screws for 2 turns from their closed state. There will be 2 screws; high speed and idle mix.

Start the trimmer and allows its engine to warm up for at least 4 to5 minutes. Keep the throttle a bit open. Now you have to turn in the low-speed jet until the engine starts to turn off. Back the jet for another ½ turn.

Keep the throttle at maximum and turn in the high-speed screw, until it starts shutting down and then back it for another ½ turn. Keep the throttle at maximum and start turning in this screw until the engine starts moving at high revolution. Then, back this jet to a position where the engine slows down. You have to try and keep the jet in between these two positions.

You might need to play a lot with the low-speed jet to get immediate response from the throttle and a smooth idle state. Similarly, you need to invest some time with the high-speed screw. Once you find its smoothest position, back the screw for ¼ turn or something in a similar range.

Some back turns are helpful when the engine works under high load. Apart from the carburettor cleaning and adjustment, you need to take care of the oil/gas mix ratio. If you own a trimmer with a fixed carburettor, then simply clean it because there are no adjustments. You can see the best petrol strimmer reviews here.

Spark plug

The mixture of air and fuel inside the combustion chamber is ignited by the spark plug. So, it’s one of the first components that you should insect. Remove the plug carefully and check its status.

An inaccurate mixture of oil and gas can make the spark plug oily. Check for corrosion, breakage, deposits or melted parts. If you notice any of these negative symptoms, it’s time to replace the plug.

Air filter

A filter maintains a clean airflow inside the engine and stops small particles to enter and damage its internal parts. So, an air filter might clog over time. Once blocked with dust and debris, it cannot supply the required amount of oxygen to your trimmer’ engine resulting in power loss.

Find the air filter, take out this component, clean and reassemble it. Replace the part if you cannot reuse it. Follow this step regularly to avoid any problems in the future.


Fuel filter

This component stops dust particles and debris from entering the engine or its carburettor. Remove the fuel filter using a hook and inspect it to see if there are clogs to block the fuel flow towards the engine. Replace the filter if it looks faulty.

A fuel filter is inexpensive and it's best to replace this component frequently as a part of your trimmer’s maintenance schedule. If you don’t find any internal filter in your trimmer, then you should follow its fuel line to locate the filter. Generally, you can find it near the carburettor. Follow the arrow to follow the right fuel flow direction.


A damaged gasket will allow extra air into the trimmer and its engine, causing loss of power. Take out the filter and remove the carburettor to access the gasket. Check its condition and replace it if required.


Final talk

Regular servicing is very important for all the gardening equipment. So, if you want the trimmer to last for many more years to come, then maintain it regularly. Clean the unit after each usage. Use a damp towel to remove all the dirt and grass clippings. Apart from that, check all the above-mentioned parts at the starting and end of the growing season. Read more: mailboxnationwide