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Lawn Mower Repair Tips

How To Troubleshoot A Lawn Mower Ignition System

If you believe that your lawn mower does not have any spark, a thorough test of the ignition system is in order.

There are two main times that a lawn mower will not develop spark.

The first is during the initial startup and the second is after the lawn mower has been running for a while.

Let’s start with no spark on startup. You attempt to start the engine and believe that there is no spark. Obtain a spark tester and place it in line with you spark plug wire. Crank the engine over and see if there is spark. If you see a bright blue spark, then the problem is not ignition related. If you have no spark, disconnect the black or gray kill wire that is plugged into the ignition coil. With this wire disconnected, if the engine starts, you will not have a way to shut it off, so plan for that! If the lawn mower does start, then the problem is in the kill system circuit and that will need to be inspected to find out the source problem.

If the lawn mower was running for a while and then you lose spark, install the spark tester to determine if you have a no spark condition. If you have no spark, the most likely item that will cause this is a bad ignition coil. Replace the coil and retest the lawn mower for spark.

Lawn Mower Repair Tips

Lawn Mower Keeps Running Low on Oil

Is your lawn mower using more oil than it should? Are you not seeing any leaks or no smoke coming out of the exhaust?

Any internal combustion engine is going to use oil over time. As your engine is running, oil will seep past your piston rings and be burned up in the combustion process. It can also evaporate as well. It really doesn’t matter whether you are using conventional or synthetic oil as they both will burn or evaporate over time.

If the oil usage is excessive, then something must be done to correct the problem. The lawn mower engine must be given a leak down test to determine where the oil leak is coming from. It could be something as simple as a valve guide oil seal or more complex like the piston rings. A leak down test will tell you what the problem is and get you on the right track to troubleshooting this problem.

Once you know exactly what the nature of the high oil consumption is, then you can repair or replace those components and test the engine to be sure that you have resolved them.

Lawn Mower Repair Tips

Lawn Mower is Blowing Out Black Smoke

If you are seeing a stream of black smoke blowing out of your exhaust pipe, your lawn mower is running in a rich condition. In other words, it is getting too much gasoline and not enough air into the engine. This makes for an excessively rich condition and will eventually foul the spark plug and carbon up the cylinder.

The first easy thing to check is the air filter to make sure that it is not clogged with dirt and grass clippings. A restricted air filter will decrease the amount of air coming into the engine and can cause this very condition.

If you have a pre-filter, it can also cause the problem. These filters can be washed and reused in many cases. Use some mild dish detergent and hot water and then wring them dry and let them sit out in the sun to dry out.

The other culprit is usually a poorly adjusted carburetor or if you are at high elevations, the wrong main jet is in the carburetor. Many carburetors today have no adjustments, but you can change out the main jet on many models of carburetors.

Look at each area of your lawn mower to determine which of these is causing the problem and correct them if needed.

Push and Self-Propelled Lawn Mower Repair

Self-Propelled Lawn Mower Stalls in Tall Grass

Are you trying to bush whack some really tall grass and your lawn mower is not cutting it? Does it start to bog down as you ease into that tall grass and then will die?

Well, the reality of this situation is that you are probably biting off more than you can chew! A self-propelled lawn mower is not a garden tractor that will cut down tall grass. You need to manage your lawn better and cut it on time. Yes, there are times when that is not possible, but it really is a lawn management problem and not necessarily a lawn mower problem.

The problem with tall grass is that it collects under the deck and starts to clog it up. When it clogs up, the blade will stop spinning and that is what stalls out the engine on your self-propelled lawn mower.

Yes, you could have an engine efficiency problem with the lawn mower if the grass is slightly taller than normal and that would need to be checked out. It could be a fuel or ignition problem or it could simply mean that your lawn mower blade needs sharpening.

By determining if the problem is with you or the lawn mower is the first step to resolving the mower stalling in tall grass.

Riding Lawn Mower Repair

Riding Lawn Mower Won’t Crank Over

Won’t crank over is a broad definition. So what does that actually mean? Do it mean that when you turn the key and nothing happens or you turn the key and the starter engages the engine but does not turn it over? Or does it mean that the starter turns the engine over but the engine does not start?

Definitions mean things and communicating the right thing to your small engine repair technician can help eliminate a lot of troubleshooting that could have been avoided.

When we know the exact problem to diagnose, we can get right to that problem and begin to systematically work on the riding lawn mower.

If nothing happens when the key is turned, we will check the battery first to see if it is fully charged. You want to see at least 13.1 Volts DC and then it should be load tested to ensure that it has the correct amount of cranking amps. Amps are the force that moves the electricity through the battery cables to the starter. If you don’t have enough amps, you may just hear a clicking sound coming from the starter.

If the engine cranks over but does not start, then an ignition system diagnosis will be needed and possibly the fuel system. You will need to systematically rule out which one is not working as it should and repair or replaced components in the system.

Push and Self-Propelled Lawn Mower Repair

Push Lawn Mower Mows For a While and Then Dies

Is your mower doing just fine on a hot day and then suddenly it dies? Does it die all of a sudden and then will restart after a while? Does it seem to run fine on a cooler day?

These are symptoms that point to a bad ignition coil. An ignition coil provides the spark to the spark plug that provides the ignition to the air and fuel mix in the cylinder. If you lose that spark, then the engine will immediately die and will not restart.

Ignition coils are known to break down when they get hot. The internal windings can form a break in the wire and as the temperature grows inside the coil, the wire can separate and cause the spark to stop. As the ignition coil cools down, the wire will reattach itself and then the lawn mower engine will start up once again. It tricks you into thinking that there is some other problem with the lawn mower that is causing it to die. You start searching the fuel system in most cases to try to find out what the problem is.

By checking the ignition system first, you will avoid troubleshooting the entire engine and find your results quicker.

Riding Lawn Mower Repair

Riding Lawn Mower Brakes Don’t Work

The brakes on a riding lawn mower are almost in two categories. We often use the transmission as a brake to slow us down or allow us to slowly let us down a hill. The go pedal or the handle for our hydrostatic transmission does a lot of work to keep the lawn mower under control.

On the other hand, the brake pedal is to bring us to a stop quickly or to hold the lawn mower and keep it from rolling.

The riding lawn mower brake is often a small disc brake that is mounted on the transmission. When you depress the brake pedal, it pushes a small brake pad against the disc to stop the transmission from rotating.

This type of brake has a few problems if not property maintained. One problem is that they almost never get adjusted as the brake pad is wearing out. So you must push the pedal down further as the brake pad wears out.

Another problem is that grass clippings, mud and twigs can get thrown up in the brake and cause it to stop working.

Lastly, a fluid leak in the transmission can cause the brake pad to get wet and lose its friction ability on the brake disc and not allow the disc to stop rotating.

Check all these items out carefully and make the repairs necessary to resolve your riding lawn mowers brake problem.

Riding Lawn Mower Repair

Riding Lawn Mower Surges at Idle

Is your riding lawn mower not working exactly like it should. Does the engine surge up and down when you start it up and idle warming up the engine? A constant rev up and down of the engine is called surging. It is like the engine gets some gasoline and then it doesn’t and slows down.

That is actually what the engine is doing. A small bit of gasoline comes into the engine and then it doesn’t receive any and then it nearly dies and then another small dose of gas arrives and then the cycle begins over again.

This is called a lean surge when the engine is not getting enough gasoline to air fuel mixture. A lean surge can be caused by the carburetor jets being plugged up or an air leak in the intake tract. Air leaks will cause too much air to enter the intake and reduce the vacuum pulling through the carburetor which in turn reduces the amount of fuel being pulled out of the main jet. Then the surging begins.

An air leak can be in the carburetor itself or in the intake manifold or where the carburetor connects to the engine such as an intake gasket leak. Check all these areas carefully to find any air leak before you go and pull the carburetor apart to clean and inspect it.

Push and Self-Propelled Lawn Mower Repair

Push Mower Takes a Lot of Pulls to Start

It sure can be frustrating when you have to pull your lawn mower pull cord more than 2 times to get your mower to start. You pull and pull and nothing until finally it fires back to life. A normal push lawn mower should start in 2 pulls. If it doesn’t, then it is having a problem and that problem needs to be discovered.

It could be something simple such as a bad spark plug or that you might not have any gas in your lawn mower. It could also mean that your carburetor is getting plugged up and needs to be cleaned. Stale gas can also sit at the bottom of the float bowl and not have enough volatility to light easily.

The timing and valve adjustment could be incorrect as well. Check the clearances on both the intake and the exhaust valves to be sure that they are within specifications. Also check the flywheel key to be sure that it is not sheared. A partially sheared flywheel key puts the engine out of time and will make it harder to start.

By systematically eliminating what it is not, you can resolve the problem with your push mower taking a lot of pulls to start.

Zero Turn Lawn Mower Repair

Zero Turn Lawn Mower Loses Power When PTO is Engaged

If you are experiencing sudden power loss when you pull on the PTO knob, there is obviously a problem. If the lawn mower engine practically dies and doesn’t want to cut the grass or move for that matter, then you have most like lost a cylinder or you have something wrong with the carburetor or fuel injection system.

Rapid power loss is a serious problem and you do not want to operate the zero turn in this condition. You want to get it checked out by a competent small engine repair shop that understands this condition and knows how to resolve it.

Trying to use the lawn mower in this condition could further damage it and that will add up to more expensive repairs. You already paid a lot of money for your zero turn lawn mower and you want it running well so you can cut your grass and make money with it if you are a commercial cutter.

Visit our Location page for a lawn mower repair shop that can assist with your zero turn lawn mower losing power when the PTO is engaged.