"Won't Start"

Article Tools

Image Gallery

Print

E-mail

Comments

RSS

And the bonus: We'll toss in several of Dennis's own shop-spun "tricks of the small-engine trade" as we go along.

First try the "Burkholder choke"--tilt the mower handle back to the ground.

Gas, Oil, Spark

Let's (ahem) get started. You cranked that mower, fiddled with the throttle switch and cranked some more, but it won't fire up. First, of course, check to see if the machine has gas. While you're at it, check the oil levels, too. For that matter, you'll probably want to change the oil. (See the sidebar "Man Makes It; Man Breaks It.")

If you're real lucky, the problem's just that oil needs to get to the rings around the engine cylinder. (A dry cylinder needs that lubrication to give it an airtight seal.) Try tipping the mower handle back to the ground for 10 seconds so oil can float back into the engine. This trick is also known as the "Burkholder choke," because it makes fuel more likely to run into the engine-thereby helping some recalcitrant machines get going. Now crank 'er a few more times. Don't overdo it; as Dennis says, "If it don't start in 10 pulls, you're sucking wind."

If you're real unlucky, you've pulled the crank rope so many times that it finally broke and came off in your hand. In that case, head off to the sidebar "Rewind Repair," and come back here when you've finished.

OK, it's got gas, oil and a good crank. But nothing, absolutely nothing, happens when you pull the rope. It's time to check the spark. You'll have to find out if the electricity needed to ignite gasoline is flowing through the engine.

Pull the wire off the end of the spark plug-you can hang it on the hook provided on the engine (Fig. 1). Then get a spark plug socket or wrench (a widely available tool), and unscrew the plug from the engine. Use steady, not sharp, force on the wrench. If the plug won't come out, squirt some penetrating oil (such as Liquid Wrench or WD-40) down along its edge, wait a few minutes, and try again. When you get the plug out, look at its tip. If that's black and grimy, clean it by running some fine sandpaper or a wire brush over both sides of the gap until shiny metal shows. You might also check the size of the gap. Most spark plugs should have an opening of around .25 mm in width (your owner's manual will list the right number). You can use a feeler gauge (another inexpensive, basic tool) to help you set that distance properly (Fig. 2). Widen or compress the gap until the appropriate gauge fits snugly in the opening. (Dennis often uses a pocketknife blade-one that he knows is close to the appropriate width-for a feeler gauge.)

Now test the plug to see if electricity jumps across its gap. To do this, hook the spark plug wire back on the outside end of the plug, and, with a stick of wood, hold the plug so its threads, but not its tip, touch a surface (preferably unpainted) on the engine (Fig. 3). Important: Don't hold the plug with your fingers. If you're touching any metal when you do your spark test- YO W! You'll get a shock that'll make you think long and hard about any more small-engine repair.

RSS | Comments | E-mail | Print