Only with the Choke Engaged Will the STIHL String Trimmer Function

When the engine is getting too much air or too little fuel, only then will a STIHL string trimmer run with the strangle engaged. Causes for this include stale gas, a fuel line puncture, a clogged fuel filter, a faulty carburetor gasket, a dirty carburetor, or a blocked fuel tank vent.

Please observe all of the STIHL manual’s safety instructions. To avoid damaging the engine while working on it, wait for it to cool down and then disconnect the spark plug wire.

String trimmer
String trimmer

Putting the Choke on a STIHL String Trimmer and Why It Won’t Start

Worn-Out Fuel for a STIHL String Trimmer

The quality and type of gas you use in your STIHL trimmer makes a significant difference in how well it operates. Varnish left behind by old gas can coat the components of the fuel system, leading to breakdowns and fuel restrictions.

The choke may be used to keep the gas-to-air mixture necessary for combustion constant when fuel flow is reduced.

Always use new gas and blend it correctly with 2-cycle oil to minimize future fuel-related issues. If you use a fuel stabilizer, use the fuel within thirty days and store it for no more than 60 days.

The recommended ratio for gas and oil in STIHL string trimmers is 50:1. Use unleaded fuel with an octane rating of 89 or higher and no more than 10% ethanol by volume.

Combine with premium two-cycle motor oil. If you’re looking for advice on fueling and maintaining your STIHL string trimmer, you’ve come to the right place.

SOLUTION: drain the gas from your string cutter. Refuel the vehicle with a new fuel blend of gasoline and 2-cycle engine oil. To keep the fuel system clean and dry, use ingredients like Sea Foam or STA-BIL.

Put this concoction into the gas tank. Turn on the trimmer and wait for the fuel mixture to circulate through the engine. If you still need to use the strangle to keep the trimmer running, keep checking the other items on this list.

Fuel Line Puncture on a STIHL String Trimmer

Choking back the airflow into the engine’s carburetor is necessary when excessive air is being supplied.

Look for a hole in the fuel line that could let air into the system.

One solution is to switch out any fuel line that has become damaged or cracked. If you find a clog in the fuel line, you should either have it cleaned or replaced.

String Trimmer with a Leaky Carburetor (STIHL)

The area around the gasket that covers the opening behind the carburetor is another possible source of excessive air intake. The quality of the seal provided by this gasket can degrade over time.

This results in the trimmer running lean due to an excess of air and a deficiency of fuel. It might be necessary to use the choke in order to keep it running.

Access the carburetor by dismantling the bolts and linkages holding it in place. Take out the gasket and carburetor.

After replacing the gasket, the carburetor, bolt, and links can be reattached. The STIHL trimmer’s carburetor can be removed for cleaning if that becomes necessary.

STIHL String Trimmer with Clogged Fuel Filter

Clean fuel for the engine and fuel system is filtered in the tank using a fuel filter to remove contaminants. The filter can become clogged and prevent enough fuel from getting through if it isn’t changed regularly.

To lessen the possibility of the filter causing a fuel restriction, I advise replacing the filter once a year and always using clean, fresh fuel.

SOLUTION: Swap out a clogged STIHL fuel filter. Before taking off the fuel tank cap, give the area a quick wipe to prevent any dust or debris from entering the tank. The tank filter needs to be removed.

To remove the filter from the tank, hook the fuel line with a clean, bent wire. Pull the used filter out of the tank and replace it with a new one that is attached to the fuel line.

Be sure the filter is level with the tank’s base. Replace the fuel cap.

A STIHL string trimmer with a dirty carburetor.

The carburetor controls the amount of fuel added to the air for combustion in the STIHL string trimmer.

The carburetor’s ability to deliver fuel to the engine can be impaired by the accumulation of varnish and gummy deposits. It’s possible for its tubes to clog up and its internal parts to get stuck, causing it to stop working properly.

SOLUTION: Clean your carburetor yourself if you’re at all mechanically inclined. To remove deposits from old fuel, disassemble the carburetor and clean it with a carburetor cleaner.

If the carburetor still doesn’t work after cleaning, you’ll either need to find a rebuild kit to try fixing it yourself or buy a new one.

Think about the cost of a new STIHL string trimmer and how good your current one is before shelling out cash for a replacement carburetor.

It may be more cost-effective to replace the STIHL string trimmer than the carburetor on a beginner-level trimmer. Depending on the model, age, and cost of repairs, you may need to make a financial decision.

String Trimmer by STIHL with Blocked Fuel Tank Vent

To maintain a constant pressure inside the tank, it is necessary to allow air to flow through the fuel tank’s vents. Because of the vacuum that would form inside the tank without a vent, fuel delivery to the engine would be severely reduced.

As a result, you may need to keep the trimmer running by applying the choke. If your trimmer is sluggish with the choke off but picks up speed once you loosen the fuel cap, you may have a fuel tank vent problem.

SOLUTION: The STIHL string trimmer should be used on a flat surface. Gas can cap should be loosened, but spillage should be avoided. Let’s get the trimmer going. Choke should be turned all the way off.

If you find the trimmer operates smoothly with the choke off, you can leave it that way by simply tightening the cap. If it stops working, it may be because the fuel tank vent was blocked.