Lawn Mower Backfires for Dummies

Flywheel key 

It's always amusing to our staffers to watch the freelancers who clearly lack the requisite knowledge attempt to explain something that's even the slightest bit technical. Oh, the misused terminology, the fumbled definitions, the bizarre constructions...  Anyway, that's what one of our staffers thought when she ran across a post at Hunker.com, freelancer Jack S. Waverly and his "explanation" of "Why Does a Lawnmower Backfire?"

Waverly, who claimed to have harvested his information from a 1994 internet post, apparently didn't actually read it. Instead, he seems to have used some reference to engines in motor vehicles instead of small engines. Let's take a look... first, Jack had to "define" a backfire:

"Backfire in engines is caused by simple chemical malfunctions that can be easily rectified."

A "chemical malfunction"? Is this yutz kidding? It's a mechanical malfunction, you idjit. Adding to the evidence that Waverly has no idea what he's talking about is this line:

"If pockets of unspent fuel enter the engine before the valves close or escape to the exhaust system, a backfire occurs. Unspent fuel ignites when a spark occurs in close proximity to the fuel pocket."

A "pocket" of fuel? WTF? Maybe he's thinking in terms of a packet of fuel-air mixture in a fuel injection system. but in truth, who knows? Waverly went on to blather about fuel pumps – most walk-behind mowers do not have a fuel pump, relying instead on a gravity feed – fuel filters, and spark plugs. He doesn't mention a common problem – obstruction in the exhaust, and then gives EXTREMELY short shrift to a fairly frequent cause for lawnmower engine problems, the timing. All Jack says on that point is,

"Check the timing of the motor."

Jack, Jack, Jack: maybe if you had known what you were talking about you would have spent less time pretending to know the topic and more on a copy-paste-reword of information about the timing. This problem most often happens when the mower hits a heavy object and stops suddenly. The flywheel key shears partially or entirely, and the magnet that initiates a spark is in the wrong location. That's what is meant by "timing" in a one-cylinder small engine.

Jack didn't know that... but we did. That's whey Jack is a recipient, and we're the people giving him the Dumbass of the Day award.

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DD - SMALL ENGINES