While you may still be able to use your string trimmer with the choke on, it’s important to isolate the root cause requiring the need for air to be restricted. Repair the problem to get your string trimmer performing at its best.
An ECHO string trimmer may only run with the choke on when the engine is getting too much air or not enough fuel. This may be caused by old gas, a punctured fuel line, a plugged fuel filter, a bad carburetor gasket, a dirty carburetor, or plugged fuel tank.
Remove the spark plug wire prior to making any repairs. Be cautious and follow all safety procedures in the ECHO operator’s manual.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
6 Reasons an ECHO String Trimmer Only Runs With the Choke On
Old Gas
Gas can wreak havoc on a string trimmer fuel system causing fuel restrictions when it’s been sitting for long periods. The varnish left behind can gum the fuel system reducing the amount of fuel getting to the engine.
In order to maintain the right ratio of gas-to-air required to form combustion, the choke may have to be used. To reduce fuel-related problems due to old gas in the future, always use the right gas, mix it properly with 2-cycle oil, and consume it promptly.
Because gas can begin to degrade as soon as 30 days after purchase, only purchase enough gas that can be consumed during this time.
An ECHO string trimmer requires gas and oil mixed at a rate of 50:1. Always use gas with a minimum octane rating of 89 and a maximum ethanol content of 10%. Using gas with higher ethanol contents can cause carburetor and engine damage.
Read more about choosing and caring for the gas at This is the Gas and Oil Fuel Mix ECHO String Trimmers Use.
SOLUTION: Remove old gasoline from your string trimmer. Add fresh fuel that includes an additive like Sea Foam or STA-BIL to stabilize the gas, clean the fuel system, and reduce moisture.
Start the trimmer and allow it to run to work the treated fuel mixture through the system. Keep checking other items if you continue to have to use the choke to keep the trimmer running.
Puncture in the Fuel Line
When too much air is getting to the engine, the choke must be engaged to reduce the amount of air entering through the carburetor throat.
Look for a puncture in the fuel line that may cause the trimmer to suck in additional air.
SOLUTION: Remove and replace any damaged or cracked fuel line.
Plugged Fuel Filter
Another item that can restrict fuel flow is a plugged fuel filter. A fuel filter is used to prevent dirt and other debris from running through the fuel system and engine.
When the filter isn’t changed regularly or you’re running very dirty fuel, it can become plugged not allowing sufficient fuel to pass through the filter. It’s best to stay on top of your fuel filter maintenance by changing it out annually.
SOLUTION: Replace a plugged fuel filter. The filter is located inside the fuel tank. Wipe around the fuel tank cap before removing it to keep dirt from falling into the tank. Pull the filter out of the tank.
A clean bent wire works well to hook the fuel linen to pull the filter out of the tank. Remove the old filter and attach a new fuel filter to the end of the fuel line and place it back inside the fuel tank. Reinstall the fuel cap.
Bad Carburetor Gasket
The gasket that sits behind the carburetor can deteriorate and become worse over time. When this happens, it no longer seals properly allowing additional air into the system causing it to run lean.
This is when there is a higher concentration of air and less fuel than required by the engine.
SOLUTION: Gain access to the carburetor and carefully remove the linkages and bolts attaching the carburetor. Remove the carburetor and gasket.
Reinstall a new gasket and reattach the carburetor, bolt, and linkages. You may need to clean the carburetor while it is removed from the ECHO trimmer.
Dirty Carburetor
The carburetor’s function is to regulate the amount of fuel that is mixed with air to form combustion to start and run the string trimmer. A buildup of varnish and deposits can make the carburetor not function right so it isn’t able to get fuel to the engine.
SOLUTION: If you are a little mechanical you should be able to handle cleaning your carburetor. Clean the carburetor by taking it apart and using a carburetor cleaner to remove deposits left behind from old fuel.
If the carburetor does not function after being cleaned, you may need to be able to find a rebuild kit to rebuild the carburetor or you may have to replace it.
Carburetors for an ECHO string trimmer can run between $60-$100 depending on the model of your string trimmer.
Before spending money on a replacement carburetor, evaluate the condition of your string trimmer and the cost to replace it with a comparable string trimmer.
You may be better off replacing the ECHO string trimmer and not replacing the carburetor. It’s a financial decision you will have to make based on the string trimmer model, its age, and the cost of repairs.
Plugged Fuel Tank Vent
The fuel tank must vent to allow air to pass through the tank to equalize the tank pressure and air pressure. Without a vent, the fuel tank will create a vacuum that will restrict the amount of fuel getting to the engine.
This may cause you to have to run the trimmer with the choke on. A good indication you may have a fuel tank vent problem is when your trimmer runs for a while before it starts to run sluggish or shuts down.
SOLUTION: Place the string trimmer on a level surface. Loosen the cap and don’t allow gas to spill. Start the trimmer. Place the choke in the off position.
If the trimmer runs well with the choke in the off position, tighten the cap and allow it to continue to run with the choke off. If it dies, you may have to replace the plugged fuel tank vent.