How Troubleshoot a Lawn Mower
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How Troubleshoot a Lawn Mower

How to troubleshoot lawn mowers before taking them to costly repairs.

To date most hourly repairs for simple lawn mowers is between 20 to 35 dollars an hour. Some lawn repair shops have gone as far as to provide a minimum cap on repairs prior to contacting the customer, normally about 75 percent of the value of a lawn mower. What this does, it provides the technician the parameters to troubleshoot the lawn mower, make minor repairs in the process of fixing the overall machine. 

For instance, if an item comes in for will not start, the simples problem could be a fouled spark plug, which in turn would only cost the customer 20 dollars plus part. Same lawn mower may start after the spark plug has been changed but hunts and surges, which could be contributed to bad fuel or clogged air filter. The technician has at least 40 more dollars to work with without having to stop the troubleshooting and contacting the customer, may or may not be at home.This is called bench time and can cause backups in a shop. Having stated these facts, here are some helpful troubleshooting tips that may keep your lawn mower from going in to a shop in the first place. As stated before in some of my helpful hint articles, get familiar with the owners manual to your particular machine. Above all practice safety and use the proper tools.

 For practical purpose I will use a simple, flat head, single cylinder ( meaning only one spark plug) standard push style lawn mower. Motor brand generic, yet 4 cycle, meaning straight gas non mix carburetor. If all of this is too much, let me highly recommend that the lawn mower be taken to a shop. No  harm meant here, except that  there are tons of lawn mowers out there every day not running solely by costumer induced problems and the repairs as stated in the intro are not cheap.

 Will not start: Follow these simple steps of troubleshooting and the machine may continue to work for you.  First, if the machine just stopped running while cutting then : Check fuel. Check the fuel cap. If a fuel cap becomes clogged the fuel air flow through the tank is interrupted and the carburetor cannot draw the fuel. Also on the most new mowers, there is a dust cap that goes in between the fill cap and the gas cap on shipping. It is to be discarded once the fuel is filled.Surprisingly most new customers keep this dust cover. Yes the machine starts but shuts off.. There is even a picture on the dust cover showing a discard picture. Check the freshness of the fuel. If the mower ran but once the fuel from a container found in the garage or under the porch was introduced  and now the machine refuses to run, it is the stale fuel. Stale fuel has a distinct unpleasant odor. Dispose of the fuel in an environmental safe way and refill with fresh fuel. If the container for the fuel happens to be a metal type, discard this container entirely and replace it with a plastic one. Metal will rust over time from the break down of the fuel and water.When this mixture is introduced to the carburetor it spells a no start. Check for clogged air filter. On most lawn mowers either the paper meshed air filters are present or a foam type air filter. The foam type is washable in soap and water and the a light lube of oil is introduced. This light coat of oil acts as a sand catch to prevent dirt from getting into the carburetor body.

The paper filters may become clogged or wet from sitting out , which will prevent air flow . Replace the air filter. Now check the spark plug. Be careful when removing the spark plug wire from the spark plug. Do not pry or use pliers on the wire. This will cause damage to the ends and leave an open spark gap. Try to pull straight out with small circular motions. Remove the spark plug with a spark plug socket or if provided with the mower, a spark plug wrench. Check the condition of the plug. The ends of a spark plug can tell you allot of what is going on with your mower. There is also a chart in your owners manual that will depict these readings. Oil covered spark plug could indicate over fill of the oil, oil burning and piston ring problems. White liquid or clear could mean water in the fuel. Broken or damaged spark plug or just totally crusted should indicate replacement. Of all the above mentioned, start with just replacing the spark plug. If all of these steps have been followed, try giving her a pull. If she starts , congratulation.

 There are several factors that will contribute to a lawn mower not starting. Here I have gone over just a few. Remember to understand your particular limitations. The use or availability of the proper tools . Your working knowledge of your machine or just machines in general and understanding what lead up to the will not start. The later is the most important, for the shop will need to know this also in case you cannot find the problem. Too many customers get a rude surprise  at times when the technician finds the cause could be something as embarrassing as the missing dog leash finally found , wrapped around the blade. That would be a 35 dollar dog leash! So keep smiling, keep cutting and hey let's grow something!

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Comments (1)

I have a simple Poulan push lawn mower and the owner's manual looks like a small book. It would be like a part-time job just to do all the maintenance stuff they recommend. It started up right away after a long winter layoff and I cut grass for the first time. Stale fuel or not, I don't argue with success. I do have an antique push mower (that's no engine) which ways like 25 pounds. That's my backup and the one I use to cut the front part or maybe the entire lawn if I feel like a total workout. No sparkplugs, no gas, no clogged fuel lines, etc. Maybe the old-timers knew something after all?