LITTLE ROCK — Come the middle of summer, my lawnmower gets harder to start and seems wheezy compared with when I begin mowing in spring. I do give it an annual tune-up then and always run it on fresh fuel. What’s causing this?
In general, the typical small engine on a mower needs a tuneup about every 50 hours, or once a season - whichever comes first, says Roy Berendsohn in a recent issue of Popular Mechanics. He quoted Dennis Blair, technical service department manager for MTD, which makes lawnmowers and outdoor power equipment: “Machines used under heavy loads such as high ambient temperatures, dusty conditions or tall grass will require more frequent servicing.” Much of Arkansas seems to fit that description during our hot, dry summers.
Berendsohn’s first guess is that your mower’s problems may stem from the alcohol (ethanol) content in today’s fuel blends.
The alcohol in the fuel oxidizes to form a tenacious varnish inside the carburetor, which attracts moisture that causes corrosion, he wrote. When it’s not doing that, the alcohol stays busy damaging plastic fuel components. He refers readers to “Alcohol Awareness,” an article on page 93 of the February 2011 issue.
Even though you try to run the motor on fresh fuel, there are several things you can do to improve your fuel supply and storage.
Use gasoline that has an octane rating no lower than 87, with an ethanol content no higher than 10 percent (E10).
Buy only enough fuel to last two weeks.
Take some fuel additive to the gas station and pour it into your fuel container before you fill up.
Consider prepackaged fuel such as Small Engine Fuel (SEF). It’s expensive compared with fuel from the pump ($5.50 to $7.50 per quart), but it’s 94 octane and completely free of ethanol. Or check pure-gas.org, which lists gas stations selling ethanol free gasoline (there aren’t lots of them around anymore).
If yours is a hard-working machine, other problems can emerge by midseason. The air cleaner gets clogged with dirt; the blade dulls; and if you do your cutting in the early morning when the grass is wet with dew, the underside of the mower deck gets plastered with a thick layer of grass clippings.
Here’s Berendsohn’s midseason checklist of mower checkpoints:
Scrape the deck.
Disconnect the spark plug and siphon out the fuel tank or remove it, then tip the mower back and give the deck a thorough scraping with a putty knife and a wire brush.
Sharpen the blade
- Remove the blade and sharpen it with a mill bastard file. Take off an equal amount of metal from both sides - you can check by balancing the blade on a bolt clamped in a bench vise or by using a store-bought blade balancer. Employ a torque wrench when you reinstall the blade; tighten the blade-retaining bolt according to the specifications in the owner’s manual.
Check the plug.
Install a new, properly gapped plug after 100 hours of operation or once a season, whichever comes first.
Service the air filter.
According to engine manufacturer Briggs & Stratton, paper or foam filters should be replaced every 25 hours of operation, while paper filters that have a foam filter precleaner last for 100 hours of operation. Never use compressed air to blow out a paper air cleaner because you run the risk of perforating the paper. “A teaspoon of dust that makes its way past a hole in the air filter can destroy an engine,” Blair says.
Clean the flywheel.
If your mower sees more than 4 hours of use a week or runs in dusty and dirty conditions, uncover the flywheel at midseason and brush off the fins with an old paintbrush.
HomeStyle, Pages 31 on 07/16/2011