A day in the life of a small engine mechanic...
Lately I have been flipping lawn mowers pretty well. I have bought and sold 4 so far, and I have a few more to work on. Today I got one ready to sell, so I wanted to share how that normally goes and how I diagnosed the problems on it. This particular one is a a little newer than a 'normal' mower. This one has a few flashy features such as an electric start and it is self propelled. Which means it should be more sought after than some others. When I picked it up, I pulled the cord and heard an awful noise, but I was pretty sure it was the blade. I took a quick peek at it there just to be sure. It was really loose. After getting it home, I replaced the blade and it ran very poorly.
Bad gas has a very...well, bad smell. It will be pretty evident if the gas is bad, plus if it is yellow or green that's another sign. I realized I needed to clean the carb, so I went ahead and removed it then cleaned it. I will post on how to clean a carb within the next day or so, so be on the lookout. Doing this helped a little bit, but it was still misfiring horribly. I did a few easy tests to see if it was the fuel delivery (carb). These tests include spraying starting fluid in it to see if it changed tune, then covering the intake with my hand to minimize the air flowing into it. Doing this will show if you have an air leak somewhere. I narrowed it down to spark...then it dawned on me.
The blade was loose! I immediately started tearing it down to get to the flywheel. Why? Well, lets say you come up upon a big rock that you hit with the blade...first, it will either bend or break something. So, the blade bolts to one end of the crankshaft in the engine, and the other side of the crank shaft has a flywheel bolted to it, which also tells the ignition coil when to send a spark to the spark plug. A small metal piece threw off the whole engine..see below.
A flywheel key which is just a small piece of metal aligns the crank and flywheel. So, back to that rock...she must have hit something big, because it loosened the blade, but it also sheared the flywheel key which then caused it to just send spark to the plug at random times rather then being in sync and firing when it needed to....bingo, misfire. I went to buy a new one ($1.30) and replaced it all and fired it up...it ran great!
After all of that I gave it a quick wash, and this mower is now for sale! I actually got this for free for helping move some furniture around a house. I tried to offer her some money too, but she declined. I put about $17 worth of parts on it, and I think I should get $150 for it. Win!
