Top 3 Reasons Your Gas-Powered Edger Won’t Start

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To give your newly-mown lawn that neat and tidy look, you’re going to want to use your edger to provide the finishing touch by trimming the grass that runs alongside the driveway and sidewalk. But what do you do if the edger refuses to start? Consult your repair partner – Repair Clinic; we’ve identified the top three reasons why a gas-powered edger won’t start. By way of explanation, a primer on gas-powered engine operation is required.

Gas-powered edger operation explained

While electric edgers can be powered by an extension cord or battery, smaller gas-powered edgers, like the Craftsman SE2200 edger, utilize a two-cycle engine to operate while larger models, such as the highly-rated Generac LER1135GMNG 9-inch edger, rely on a four-cycle engine.

What’s the difference between a four-cycle engine and a two-cycle engine?

Similar to car engine, a four-cycle engine draws gasoline from its fuel tank and has a separate sump for oil. A two-cycle engine requires the gasoline to be mixed with the oil for the engine to operate properly. If you don’t get this mixture right, a two-cycle engine can seize due to insufficient lubrication. For this reason, a four-cycle engine is the easier engine to maintain (just pour the gasoline into the tank as you would for your car and remember to change the oil regularly). If you’re concerned about getting that gas/oil balance right for a two-cycle edger engine, you can use a pre-mixed fuel and oil product like TRUFUEL 50:1 Mix to fill the tank.

How does a four-cycle edger engine start?

Since we’re talking about what causes an edger engine not to start, how does a four-cycle edger engine start? When the starter rope is pulled, the starter engages a starter cup on the flywheel and rotates the crankshaft. The rotating crankshaft connects to the piston which moves up-and-down within the cylinder and ignition process begins. The flywheel has permanent magnets built into it, and as it rotates past the ignition coil, a magnetic field is created. The magnetic field induces electricity, allowing the ignition coil to send voltage to the spark plug.

At the same time on a four-cycle engine, the piston will travel down the cylinder creating a vacuum which draws fuel and air through the carburetor where they mix before entering the cylinder through an intake port. This action is called the “intake stroke”. Next, the “compression stroke” takes place as the piston travels back up to the top of the cylinder and the intake valve closes. The spark plug now fires and ignites the fuel and air mixture which forces the piston down (known as the “power stroke”). The momentum of the spinning flywheel provides enough force to push the piston back up. The exhaust valve will then open, and the combustion gasses will exit through the muffler in what is the fourth and final cycle – the “exhaust stroke”. A four-cycle engine will continue to run and repeat these four cycles until it is turned off.

How does a two-cycle edger engine start?

How does a two-cycle edger engine start? Similar to a four-cycle engine. As the two-cycle engine’s piston travels down the cylinder, it exposes an intake port and pumps gas, oil, and air into the cylinder. As the piston travels back up the cylinder, a vacuum is created and the gas, oil, and air is drawn through the carburetor into the crankcase. When the piston reaches the top of the cylinder, the energized spark plug will ignite the fuel and air mixture, driving the piston down, exposing an exhaust port where the spent fuel exits. A split second later, the intake port is exposed again. Fresh fuel is drawn in and the process continues with every revolution of the crankshaft.

Four-cycle engines and two-cycle engines have similar exhaust and primer features

The exhaust from both two-cycle and four-cycle engines will travel through the muffler and, often, a spark arrestor. The muffler reduces engine noise while the spark arrestor prevents burning carbon deposits from exiting the engine and, potentially, starting a fire.

Engines will have a choke, primer bulb, or both to assist with starting, especially when the engine is cold. The choke will temporarily restrict air flow through the carburetor so more fuel can enter the cylinder. Likewise, a primer bulb draws additional fuel through the carburetor before the engine is started.

All that engine power drives the edger’s cutting blade

On edger models using a drive belt, the operator squeezing the throttle trigger or depressing the bail arm will cause an idler pulley to put tension on the belt which will then turn the blade which allows you to neatly trim the edge of the lawn. For direct-drive edger models, squeezing the throttle trigger or depressing the bail arm will cause the engine to increase its speed from idle to run and the clutch will engage the clutch drum with its drive gear. The clutch drum drive gear engages the blade drive gear which will cause the blade to rotate.

The three causes of your edger not starting

Frustrated because your gas-powered edger won’t start? Here are the top three most likely causes you should troubleshoot:

  1. Defective spark plug – Due to carbon build-up or a weakened electrode, a spark plug will degrade over time and be unable to ignite the compressed fuel and air inside the engine’s combustion chamber to start the edger. You can use an ignition tester to help determine the strength of the spark plug, but it’s probably easier to simply replace the spark plug with a new one, something we recommend doing annually.
  2. Restricted carburetor  –  Old or bad fuel can leave a gummy residue inside the carburetor creating a restriction. This will prevent the proper ratio of fuel and air from entering the cylinder which can cause the edger engine to have trouble starting. You should always make sure you keep fresh fuel in the tank and avoid using fuel that contains more than 10% ethanol. We also recommend using a fuel stabilizer to help preserve its quality. As we mentioned earlier, if you’re concerned about getting that gas/oil balance right for a two-cycle edger engine, you can use a pre-mixed fuel and oil product like TRUFUEL 50:1 Mix to fill the tank. You can try cleaning the carburetor ports with a dedicated carburetor cleaner, or WD-40, to clear out the restriction, but if the clog is particularly bad, you may need to purchase a new carburetor.
  3. Malfunctioning ignition coil – Since the ignition coil is designed to send voltage to the spark plug while the engine is running, the spark plug will not be able to ignite the fuel to keep the edger engine running if the ignition coil is defective. As with the spark plug, you can use an ignition tester to help determine if the coil has failed and requires replacement.
Edger Won’t Start? Top 3 Reasons Edger Won’t Start.

Genuine OEM edger parts direct from Repair Clinic

When replacing a spark plug, various carburetor components, or an ignition coil to repair the edger’s engine, or installing a new cutting blade or wheel, you want to make sure you’re purchasing a genuine “original equipment manufacturer”(OEM) part to keep the equipment running at its best. This is why Repair Clinic is your best resource for finding edger replacement parts. Repair Clinic carries only genuine OEM parts from the top names in outdoor power equipment, including Craftsman, Cub Cadet, Dolmar, Echo, Homelite, Husqvarna, Kawasaki, MTD, and Poulan. You can find the right part for your edger or the edger’s engine by entering the equipment’s full model number in the Repair Clinic website search bar, then use the navigation filters to narrow the comprehensive part list down to just the part or parts you need.

Repair help from your repair partner

Want to learn the correct way to replace an ignition coil on a Weed Eater edger (Model PE550) or install a new cutting blade on the same product? As your repair partner, Repair Clinic has an extensive “Videos & Articles” library filled with thousands of procedural videos, articles, schematics, and diagrams to provide you with the repair help you need to fix your outdoor power equipment, major home appliances, and heating and cooling systems. Just enter the appliance or product model number to get started.

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