Why Does Your Trimmer Bog Down?

trimmer on the ground.

Machine bogging is a common, and arguably, one of the most annoying trimmer issues you can ever face. No matter how careful you are, some things seem destined to happen. The problem is that you might not know the cause of such problems and, even worse, how to fix them.

The most common reasons for trimmers bogging down are fuel issues, problems with the carburetor, or insufficient air intake. You can always perform a DIY fix-up for most of these problems, by cleaning the air filters, refilling the gas tanks, or unclogging the exhaust. However, if you are not sure how to do this, call a specialist.

This article highlights the various reasons why a trimmer may bog down and how to fix each one of them.


Why Is Your Trimmer Bogging Down?

Your trimmer may bog down due to multiple reasons, depending on its age, your repair and maintenance practices, and how much you follow the manufacturer’s recommendations. Here are some of the common reasons why your trimmer is bogging down.


Air Filter Issues

The air filter is a crucial component of a two-stroke engine. It conducts fresh air to the combustion chamber, enabling the ignition process. The filter also ensures that no foreign nor potentially hazardous debris gets into the engine.

In most cases, the filter clogs and blocks due to the accumulation of dirt and debris, which it helps keep away. It may also get blocked if your trimmer goes unused for too long. The most common sign of a faulty filter is when the trimmer engine starts before stopping abruptly for a few minutes.

Choke Issues

It is a common problem, especially with trimmers that operate on chokes. They require that you move the control on the grip to ‘Start,’ then turn the choke on by shifting the lever to ‘Choke.’

In these kinds of machines, choke often restricts the air movement to the carburetor, resulting in a fuel-rich mixture in the machine’s combustion chamber. Moving the choke to the opposite direction opens the carburetor, allowing air to flow.

Failure to do this causes the engine to stumble and shut as you open the throttle. In such cases, you will have excess fuel in the combustion chamber.

Your trimmer might also have too much, in which case your engine may smoke. This fills your spark arrestor screen with too much carbon deposit, eventually blocking the airflow. Carburetor Issues

The carburetor is like the heart of your trimmer’s engine. It regulates the air to fuel ratio and controls the engine’s speed. Your trimmer won’t work if the carburetor is dirty, cracked, or faulty in any way. Indeed, with a faulty carburetor, your trimmer will be hard to start. It may also bog down or die when you throttle the engine. It may also start overheating, backfiring, or producing black smoke.

Most trimmer carburetors come factory-adjusted at sea level. Using the machine at a high altitude may also cause it not to get enough air, and thus, be more prone to combustion. This problem may accumulate and cause your trimmer not to start or shut when using it.

Flooded Engine

Sometimes, you may not have the proper knowledge to fix the aforementioned issues. With that, you will have to try and fail, which can lead to other issues. Most notably, you will keep restarting your engine every time you think you got it right. After one too many attempts, your trimmer won’t start and will leave you with a flooded engine.

How to Fix a Trimmer Bogging Down?

Your trimmer may bog down due to various issues. While some are easy to fix, others might require a more technical approach. We recommend, if your trimmer doesn’t start, to begin with the easy-to-fix problems, ranging from fuel issues to dirty filters or plug problems.

Fix Your Fuel Settings

Fueling problems represent the most rampant issue with bogging trimmers. It may either be because of fuel inefficiency or problems with the fuel tubing. Or, your tank may be full of old fuel that won’t be effective due to prolonged exposure to oxygen and moisture.

Fuel Inefficiency

One primary reason why your trimmer may bog down is that you depleted the fuel in the tank. As all other fuel-propelled machines, trimmers need the right amount of fuel to function. Luckily, this is a simple problem that you can handle by yourself.

First, you need to look at your fuel chamber to ensure that your machine won’t work because you don’t have enough fuel. If that’s the problem, all you have to do is refill your tank and resume working.

Fuel Tubing

If you check the tank and discover that you have enough fuel, and yet, your trimmer won’t start, it may be time to examine your fuel tubes. Sometimes, you may be having damaged or disengaged tubing. In that case, your engine will have the energy supply it needs to function adequately.

We recommend that the fuel you use in your trimmer doesn’t remain there beyond three months. Old fuel tends to lack fluidity to reach the carburetor, preventing it from starting the machine. Also, note that oil, when mixed with gasoline, tends to form a separate layer. Thus, you need to first shake the fuel mixture before filling the tank. Doing so allows the smooth flow of the liquid in the tubing.

At times, several failed attempts to restart the trimmer may worsen the problem. In such cases, your engine will flood with too much fuel and won’t start. To fix this, you will need to drain out the excess fuel according to the manufacturer’s guidelines. Depending on the situation, you may have to repeat the procedure until the trimmer restarts.

Spark Plug Issues

If you tried turning your engine on in vain, the issue might be in the spark plug. Indeed, a faulty spark plug cannot deliver the electric current required to ignite the fuel in your combustion chamber. Two potential things could lead to such a situation: a dirty spark plug or a cracked spark plug.

Adjust and Clean Your Filters

It is another easy-to-fix problem that you should check from the beginning. Leaving your filter wide open allows excess air into the engine and may lead to choking. Similarly, debris, dust, and dirt can accumulate and clog the filters, making the engine stall.

In such a scenario, you have three options depending on the extent of the damages. If the filter is misplaced, you may have to reinstall it correctly. You may also have to clean your dirty filters, then reinstall them, or install an entirely new component.

Filters are generally inexpensive, making more sense to replace a dirty one than try to repair or clean it. When cleaning the filters, attempt to run the trimmer with loosened caps. As you may have a plugged vent hole if it runs, you will need to replace the caps together with the filters.

First, to fix a faulty filter, remove the screws that hold it in place, often located next to the front of the engine. After that, use warm water and dish soap to clean it. Then, soak it in lukewarm water thoroughly.

Give it a moment, then thoroughly rinse it to remove the remaining soap. Lastly, leave it to dry before reinstalling it.

Once you’ve completed the above tasks, switch on the trimmer and see if it runs properly. If it doesn’t, then the problem may be elsewhere and you may need to continue troubleshooting.

Fix the Spark Plugs

Bad spark plug settings are another problem that may bog your trimmer down. Dirty spark plugs are also a major issue with most trimmers, yet an easy one to fix.

You only need to pour some gasoline into a bowl and clean your spark plug with a wire brush. Once done, reinstall the plugs and check if your trimmer works. You might also scrap the dirty spark plug with a knife to remove the extra debris.

Spark plugs also crack. In this case, cleaning it won’t help, so you must buy a new one. You do not require a professional to do this for you as these components are very affordable and easy to fix.

To do this, disconnect the lid and clean the surrounding. Then, remove the component with a spark plug socket. After that, check the porcelain for cracks or scratches and determine whether you should replace the spark plug or return it after cleaning it.

Fix the Electrical Issues

Diagnosing and fixing electrical issues in your trimmer is also a very straightforward process. Start by examining whether or not the extension code is functional and if it is in the right electrical outlet. If it is faulty, replace it with a good one. We recommend you use a quality, durable cord to prevent such problems in the future.

You can also check the circuit breaker or fuse from your power source. If it is faulty, you have to fix the power source rather than the trimmer.

Repairing Carburetor-related Problems

This is yet another issue that is fairly easy to fix and doesn’t require any specific skills. Depending on your trimmer’s model, you should begin by removing the filter cover, then detach the filter.

After that, loosen the screws holding the primer bubble in place to open the carburetor, then clean thoroughly and unclog the filters.

The rule of thumb is that you get a rebuild kit to clean your carburetor. There are inexpensive models out there, but it is possible to proceed without fresh gaskets if you cannot get any.

Troubleshoot Choke Issues

As pointed out earlier, a trimmer choke restricts the amount of air that gets to your carburetor when you turn it to the ‘Start’ position. As a result, it produces a fuel-rich mixture from the combustion chamber. It would help if you always turned it to the opposite direction when your trimmer starts moving to open the machine’s carburetor and allow air to flow in freely. Failure to do so causes the engine to stumble and shut as you open the throttle because you have too much fuel in the chamber for it to ignite.

To troubleshoot this issue, you must make it a habit to clean this screen periodically. Doing this lowers the chances of your engine stalling. It is as simple as regularly replacing the air intake filters or spraying the component with compressed air if it is the felt model. On the other hand, if it is a fiat model, you can always wash it with soapy water.

Please make sure to close the choke before you start removing the air filter. Doing this helps keep dirt and other foreign objects out of the carburetor.

Fixing the Flooded Engine

Like a motor vehicle, your trimmer’s engine may flood with a highly rich blend of fuel and air. Fixing this is no rocket science. All you need to do is unflood the trimmer.

You will have to ensure that you switch the machine on and then turn the choke to the ‘off’ position.  With your hand on the throttle trigger, pull the starter recoil severally and quickly — this may take several pulls, so brace yourself. This step helps eliminate extra fuel that may remain in the combustion chamber.

Keep holding the trigger until black smoke stops coming out. This smoke is a sign that the trimmer is burning the excess fuel.

Take Your Trimmer to a Certified Repair Technician

If, after completing all these steps, your trimmer still bogs down, the problem may be beyond your ability. In such cases, we recommend you do not proceed with more trials and errors and instead take the machine to a qualified technician for a better diagnosis.

Some problems, like recoil starter issues, can be too technical if you do not have the proper skills and experience. If the recoil spring snaps, you won’t be able to start the trimmer altogether.

How Do I Know If I Have the Wrong Trimmer Fuel Mixture?

Fueling your trimmer with the right gas is crucial in ensuring your piston stays lubricated. Too much oil in the oil mixture may not lead to too much damage but will be noticeable, and you must correct it as soon as possible.

On the other hand, too little oil will cause scars on the piston while operating the machine with no oil will cause the engine to seize just a few minutes after starting it. It may also cost you a lot of money on repairs or the replacement of the unit, depending on the extent of the damages.

There are two ways to determine and fix this issue:

Too Much Oil

You can start the trimmer and let it run on idle mode to warm up. Then, press the throttle and watch the engine. If it emits blue smoke or you see oil dripping from the exhaust, your fuel ration may be too rich, meaning the machine has excess oil. You can correct this by turning off the trimmer, draining the existing fuel, and replacing it with properly mixed fuel.

Too Little Oil

Sometimes, the oil may be too lean. To determine this, press the throttle down and carefully listen to the loss of power. While doing this, touch the outer section of your engine to check if it is hot or smells like hot metals rubbing against each other.

If you notice any of these occurrences, it means that your fuel mixture is excessively lean and that there isn’t enough oil in it. Since too little oil can quickly cause damages to the engine, you must find a way to correct this.

Stop the engine immediately when you realize this. Then, drain the existing fuel and replace it with a properly mixed one.


How to Mix Oil and Gas?

Getting the right oil to gas ratio is crucial in ensuring your trimmer runs smoothly. Manufacturers are now producing newer two-cycle engines to have them run cleaner. These modern machines run on a 50:1 oil to gas ratio. To compare, older models run on a 40:1 or 32:1 gas to oil ratio. You must understand this before you mix your fuel.

Two-cycle oils come in 2.6 oz. containers, making it easy to mix with one gallon of gas to produce the desired 50:1ratio. To obtain a 40:1 ratio, you may have to add 3.2 ounces of oil to a gallon of gas.


Things to Note While Mixing the Fuel

Gas and oil are not environmentally friendly, so you must find the right way to dump the waste. The two liquids seep into the groundwater, and dumping them on the ground may contribute to the contamination of our water bodies and the degrading of our ecosystem

Gasoline loses its power with time. If you let it stay for six months, it might not be strong enough to run your trimmer.

Never use automotive oil on your trimmer. Instead, use a two-cycle oil specifically made for an air-cooled engine. Also, avoid two-cycle oils made for water-cooled engines.

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