Why are Weedwacker engines such crap?

There is no tool I hate more than the gas-powered string trimmer. What idiot decided that it would be a good idea to cut weeds with twirling bits of string? If the grim reaper were around today, he would be depicted not with a scythe, but a Craftsman gas trimmer.

I recently destroyed my second weedwacker in as many years. These run about $150 new — enough money that I don’t really want to toss it — so I hauled it to a small engine repair shop and asked for a quote.

Mechanic: “Just throw it away and buy a new one.”

E: “What?”

“It’s not worth it. It will take at least two hours of labor, and we have to special order the parts. These aren’t designed to be serviced.”

“It’s barely a year old!”

“That’s about how long they last. If you want something that you can use longer, buy an Echo. We sell and service them.”

“Wait, why does Craftsman last only a year? Is it because they’re made in China??

“No. It’s because emissions regulations mess them up. Just buy an Echo.”

I had a ton more questions but I felt guilty asking questions without buying anything, and there was no way I was gonna spend $$$$ on an Echo. So I thanked the mechanic for his time and left.

Seriously? Craftsman string trimmers crap out because of EPA regulations?

Small engines have two emissions metrics to meet: (HC + NOx) and CO. Hydrocarbons (HC) and Carbon Monoxide (CO) are the result of unburned fuel in the exhaust; Nitrogen oxides (NOx) form when nitrogen and oxygen combine at high combustion temperatures.

Historically, small engines were factory-tuned to run rich, meaning they would draw a mixture of more fuel and less air than could fully combust. Excess fuel lowers the operating temperature (evaporative cooling), and helps the engine generate more power under heavy load. A rich mixture dumps HC and CO; a lean mixture runs hotter and cleaner while producing NOx.

Handheld engines don’t have catalytic converters or electronic fuel injectors, nor do they have on-board computers that can be programmed to cheat on EPA tests. Two-stroke engines like the weedwacker produce little NOx to begin with, so the cheapest way for a manufacturer to reduce emissions is to tune the carburetor to run lean.

In older weedwacker models, the carburetor has an adjustable air screw. Air density varies depending on temperature, altitude, and humidity; so a consumer might want to adjust the air:fuel mixture to match local conditions.

EPA regulations require that any engine with adjustable fuel mixture meet the emission standards across all settings. Craftsman solves this problem by blocking access to the air screw: Everyone runs lean.

Running hot and lean shortens the life of the piston and rings and bearings, but that’s fine. According to Federal regulations, light-duty handheld engines should have a useful life of 50 hours. That’s how long they’re tested during certification, and there’s no incentive to exceed this.

There isn’t even any incentive to invest in cleaner technology, because by 2024 California will entirely ban small gas-powered engines.

Then there’s the increase in ethanol fuel blends. Ethanol is green because it’s made out of corn. It also has 33% less energy per volume than regular gasoline, which is effectively like running lean. Even worse, ethanol attracts water, which separates from the fuel and corrodes the engine. All engines are susceptible to moisture, but someone who shells out for an Echo probably knows to buy ethanol-free fuel by the can.

And that’s how EPA regulations turn small engines into garbage.

9 thoughts on “Why are Weedwacker engines such crap?

    1. Bought a Shindaiwa 7 years ago… At least 50 hrs use per year, min 350 hrs to date and still going strong. You get what you pay for.

  1. If you are not running a landscaping business then electrical DeWalt would probably work better than fiddling with gas unit. Trimmer doesn’t need that much power.

    1. True. I liked the option of being able to swap in a chainsaw attachment on the gas trimmer, but realistically I will never need that… unless zombies attack.

      1. I actually have two separate DeWalt electrical chainsaws: normal one and one on a long stick for trimming. They take same batteries as my other tools, batteries are most expensive parts.

        I finally got gas pressure washer though because electrical pressure washer really doesn’t produce much pressure.

  2. My grandparents were conservative, frugal (as in old school cut coupons and reuse boxes) and bought American. My grandma died almost 30 years ago owning the same dishwasher, iron, washer and dryer as when she and my grandpa bought their house 40+ years before. (Oh, and they retired in their late 40s. Can you hear Archie Bunker and Edith signing?)

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