Keep Your Mower from the Curb! Get Your Mower Running Again By Learning These Lawn Mower Fixes!

Ever been so frustrated with a no-start lawn mower that you were tempted to kick it to the curb, in the hopes that someone will gladly save you the hassle of taking it to the dump?

Don't be one of those people! This article will help you learn lawnmower fixes, that will allow you to save time, money and ultimately avoid the hassle of buying an expensive new lawn mower.

In many instances, lawn mowers thrown away by frustrated homeowners or users, who are unaware of the simple nuances of lawn mower maintenance and operation, are in fact easily repairable and are frequently resold, unbeknownst to the original owner.

The good news is this article will share with you easy checks anyone can do, safely and easily. to get to the bottom of their no-start lawn mower, without the use of specialty tools.

First, refer to this previous post on the importance of keeping your gas fresh, and avoid many of the causes of no start conditions from the get go, here: Why Won't My Push Mower Start? Solution: Mind your Gas!

But before we dive in deeper, its important that you understand the three requirements for an engine to function. They are: gas, spark and air. It is important to understand that 2/3rds of all small engine related repair calls pertain to fuel-related issues; namely caused by dirty carburetors. This is usually, an easy repair that simply requires disassembly and cleaning of your mower's carburetor.

Furthermore, it is important to note that failure of the ignition system (spark), causes many frustrated homeowners to give up on their machines and allow the carburetor and fuel tank to sit and become gummed up, effectively compounding their headache.

Hang on! Before you begin tearing into your unit's fuel delivery components, why not run some checks for spark?

First check: Check for Spark!

No matter how fresh your gasoline is, or how clean the carburetor is, the machine will not fire without a spark. Your spark can be assessed by first, removing the spark plug from the lawn mower, using the appropriate sized spark plug socket and a ratchet. Such a socket will have a rubber boot inside to prevent damage to the fragile shell of the spark plug during removal.

Once removed, reinsert the spark plug back into its rubber boot. Ground it out by placing the electrode tip, (the side that is normally inside the hole on the engine) against the metal of the cylinder head (the area near where the spark plug hole is). Try to position it so that it rests there on its own, but remains in full contact with the cylinder head. Now with your own, or anyone's hands safely away, depress the blade engagement bail, while simultaneously pulling the starter rope, and with the help of a cell phone camera on record, or another person, check the electrode gap of the spark plug. Warning: Do not touch spark plug, its boot, or the wire (which runs from the spark plug boot to the ignition coil (we will discuss this component later), while pulling the start rope! You may get a shock!

If you see a distinct blue spark, your ignition system is functioning correctly. You may also see a yellow spark indicating a weaker spark, but in many cases the unit will still run.

Pro Tip: Checking spark this way does not negate the proper check required using a spark tester, however this is the best method for those without access to specialty tools. Spark conditions may change while unit is running and under load.

If No Spark Discovered:

Four possible scenarios include:

• There is a short on the kill wire, (broken wire, torn insulation) that is connected mechanically, from the blade engagement mechanism to the kill wire. It effectively turns the engine off when released. Or the wire is simply disconnected, and grounding out on a metal surface. To test this, simply disconnect the kill wire from where it is connected; to locate it, follow the blade engagement cable all the way down to where the wire grounds to the switch that moves when you engage/disengage the blade engagement bar. Be warned! Your mower may start and you will not be able to stop it if kill switch is bypassed and spark plug is not removed! Take caution! If this scenario were to arise, pull the spark plug from its boot using insulated gloves, or rubber handled gripping tool (such as pliers).

• The magnets in the flywheel are weak (simply place a screw driver or socket near the flywheel magnets, they should at least attempt to pull from your hand).

• Spark plug itself is defective (you can test by swapping with a known good one and trying the cylinder head test described above). Refer to this post on how to read your spark plugs Your Spark Plug is Telling You Something...and it Never Lies: Read Your Spark Plugs Like A Pro

• Or the ignition coil (if a single part and non-mechanical; called: solid state) is not properly gapped or is itself defective.

  

  This picture details the kill switch, blade engagement bail and the blade bail cable. Operator engages and disengages Blade Engagement Bail to Start and Stop Machine.

The most common scenario causing a no-spark would be an improperly gapped ignition coil. If it is too close and making improper contact with the flywheel, it will make pulling the start rope a chore, as there should be small gap, allowing the flywheel to spin freely. Many people incorrectly associate this condition with a seized engine.

The flywheel is shown here with the ignition coil depicted with the green arrow; the two orange arrows show the adjustment bolts, loosen them to set the gap

Although, you are technically supposed to set this gap to engine service specs. using the correct sized feeler gauge, a business card-sized thickness of a gap, will usually restore spark back to your your lawn mower (if this is in fact the root cause of the no spark). Simply turn the flywheel (it is much easier and safe with spark plug removed from both the cylinder head and its wire), until the magnets meet the ignition coil. Loosen the bolts holding down the ignition coil. Notice how the holes where these bolts go are oblong, and allow movement or adjustment to take place. The coil should now be able to move freely once bolts are loosed sufficiently. Now, place the business card between the contact points, where the coil ends meet the magnets and allow the ignition coil to move in towards the flywheel magnets by the natural magnetic pull that should take place. Finally, tighten down the ignition coil bolts to set this gap.

The Spark plug is threaded into the cylinder head on all lawn mowers

If Spark is Present:

If you do have spark, proceed to fire the engine, without the aid of its fuel system by placing a squirt or drop of gasoline into spark plug hole. Less is more in this case. In fact a spray bottle would suffice, a single or two gentle squirts is all that is necessary. Be sure not to overfill the spark plug hole with excess gas!

After, gently thread in spark plug by hand first, to start threads, and preventing damage to the fragile, threaded spark plug hole; then use appropriate spark plug socket and ratchet to lightly hand tighten spark plug until it gently and briefly feels like it bottoms out. Do not over tighten!

The spark plug wire will run from the spark plug to the ignition coil. The coil is held by two small bolts and its gap, in relation to the flywheel magnets, can be adjusted

Next, pull start rope. Observe engine to see if it sounds like it is trying to start. Does it fire on its own and quickly die? If so, the good news is you most likely have a dirty carburetor. In this case it is wise to clean the carburetor and resurrect your once dead mower, and get your lawn mower running again! Refer to this post for general tips and guidelines for doing so: Learn to Fix your Lawn Mower: Fix Majority of No-Start Lawn Mower Issues Pertaining to Fuel, Yourself!

Key takeaways:

Do not assume your unit is broken and toss it!

By first checking or addressing your potential spark issue, and seeing if the lawn mower can fire on its own, this almost always points to a simple dirty carburetor condition, that can easily be fixed!

Never the Norm!