Spring Lawn Mower Maintenance

If you're like me, then you might be calling yourself an idiot right now.  I love to work in my yard.  I love the smell of fresh cut grass, but I hate when it's a over a hundred degrees in the shade, and 99% humidity and I have to get out and mow that same yard.  I love that first cool weekend in the fall when I know this is the last time I have to mow after a long hot summer.  But last year I did something real stupid, I left gasoline in my lawn mower.  Doh...

It's finally time to start mowing again and if you left gas in your mower, then like me, it won't start, or if it does, it won't run properly.  I spent a few hours yesterday morning and evening fixing my lawn mower.  Here is a few things to try and fix your mower before you take it to the repair shop, or buy a new one.

A lawn mower is a small gasoline engine that needs to be in tune to run properly just like your car.  One item that I've often overlooked was the air filter.  Just like a car, a lawn mower engine needs proper airflow to run properly.  This is also a good starting point to looking for problems.  An air filter can be bought for less than $10.00 at a local store. 

The next place to start looking for problems is the spark plug.  If you've had your lawn mower for more than a few year, I would suggest replacing the spark plug.  They cost about $3.00, and can save you a lot of frustration later.  All you need is a spark plug socket and a wrench.  Unplug it, unscrew it, take it to store, and find one that matches.  Somewhere on it you will see a code like the one pictured below.  Buy the same one, take it home, screw it in, and put the little plastic cap back on. 

Spark Plug

 To test if you're spark plug is the problem, try to start your mower.  Listen to see what kind of sound it makes.  Then unplug the spark plug, (but leave it screwed in), and try to start it.  If you hear the same sound, you can safely say you are not getting a spark.  Then you can unscrew the plug, and see if it's in a good condition. You can google to see what a good spark plug should look like. 
Hopefully, a new plug and air filter, and you're mower will be good to go.  If not, there are a few more things to try.

The first thing to do is look at you're gas.  It should be clear, if it's yellowish, then you have bad gas.  This was my problem.  Gas (especially gas with ethonal) will start to break down quickly over the winter.  According to conventional wisdome, you really shouldn't run gas with ethanol in your small engines.  I know a couple of guys that own small repair shops, and they are convinced that most of the problems with small motors is the ethanol in the gas. 

If you have bad gas, you need to drain the tank, and dispose of the gas properly.  Try the local auto parts store and see if they will recycle it for you.  Add some fresh gas, and try to start it again.  You may still have trouble getting it to run, which brings me to the last thing to try, the carburetor.

Bottom of the carburetor

I had to unscrew the bottom of the carburetor, and lo and behold I had some yellow gas in there.  No one wonder my mower wouldn't start.  I drained the bad gas out of there, put everything back together and was finally able to get my yard mowed. 

A few words of caution when messing with the carburetor.  Make sure everything is clean around it, you don't want any dirt to get inside it. I know this can be hard with a lawn mower, but make sure you clean everything around it.  Even a little bit of dirt can tear up your carburetor.  Also make sure you know where every screw goes that you take off.  Taking a photo on on your phone before removing a screw is a good way to keep track of all the pieces.  Finally, take it slowly.  Be careful not to strip the screws, bolts or the heads on any of them. 

If you follow these steps, you can probably fix most of the problems with any small engine you come across.  And hopefully you can save yourself a few hundred dollars from repair bills, or having to buy a new mower.  All these skills can also be transferred to your car engine, saving you even more money in the long run.