Lawnmower Problems

With all of the rain lately, I decided to try and take advantage of a small window of opportunity when it wasn't raining and get the lawn mowed before I lose any kids in the grass. My philosophy on push lawnmowers (and lots of small engine equipment) is that their cost is so little relative to my earnings that I will fill it with gas when it stops and fill it with oil just before it seizes up and then basically do nothing.

I don't drain the fluids before winter. I don't sharpen blades every year. I certainly don't change the oil. I did have a riding lawnmower once when I had a half acre to mow. It came with the house and was about 30 years old. It would run out of oil about once a season and semi-seize up. I would put a quart or two in it and then wait an hour for it to cool down some, and it kept on working.

Small engines are designed to take the abuse of the casual home owner. Last year I didn't mow the lawn at all (my wife did it all), this year I have noticed that the lawnmower wasn't running real smooth. Choppy, changing speeds, although right before it ran out of gas it would rev up to its normal operating speed (and then promptly die).

So, halfway through the yard I ran out of gas. Got the gas can (which has gas that is probably 1-1/2 years old and didn't have the fuel stabilizer put in it last winter), and filled it up. Normally, the lawnmower starts on a single pull. But, this time, I could get it to sputter a bit and then it would poop out again. After several minutes it was time to get some tools out and check the thing out.

First thing I did was check out the air filter. The air filter is nothing more than a sponge with a hole in it. At the intake holes it was cakes with oily grass clippings. Well, that could be a problem. The lack of air would definitely affect the engine causing it to run rich for the amount of air (explaining the sluggishness), and then working fine at the end of the tank when it was just sucking a few fumes (and getting the fuel-air mixture just right).

So, I took it inside and cleaned it with some dish soap (dish soap is good for oil - they use it to clean off animals from oil spills - or at least that is what the Dawn commercials say). While the filter was off, I decided to check to make sure that gas was spraying through the carbeurator. A couple pumps on the primer and a nice stream of gas was spraying. So, I attempted to start the engine with the air filter off. No luck, it was doing the same thing as before.

So, the next thing to do was pull the spark plug. Sure enough, it was caked with carbon deposits. One of the problems with a engine constantly running a rich mixture is some of the fuel is left on the spark plug and chamber walls. This gets hot enough to smolder, but doesn't make a clean burn. Instead, it coats the surfaces with a black carbon deposit. Eventually, this gets thick enough that the spark won't happen, hence the engine won't sustain itself.

Some wiping off with a rag and a file to clean up the sparking surfaces and I was ready to go. Put it all back together and the lawnmower started on the second pull. I let it run for a while to be sure it didn't die. So, the next time I am at Lowe's I'll probably pick up a new air filter and a spark plug. After all, I have had the lawnmower for three years and I haven't done any maintenance on it until today.