An Exmark mower won’t start because of fuel and air restrictions caused by a dirty carburetor, clogged fuel line, bad fuel pump, or plugged filters. A bad battery, charging system problem, and faulty safety switch can also prevent your mower from starting.
I have put together a list of items with steps to repair your mower to get your Exmark running again. This guide addresses gas-powered Exmark lawn mowers. For starting problems with an Exmark diesel lawn mower refer to this guide: Reasons a Diesel Lawn Mower Won’t Start.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Reasons Your Exmark Mower Has a Starting Problem
Fuel Tank is Empty
A guaranteed reason your Exmark won’t start is when you don’t have fuel in the tank to allow the mower to run. I list this well-known cause of a mower not starting because it’s an easy item to overlook in the heat of the moment.
Customers usually get upset when I ask this question while troubleshooting their starting problem because having fuel is so obvious. However, on several occasions, I have found this to be the issue that was overlooked.
Repair: Add fresh fuel to an empty fuel tank
Using the Wrong Type of Gas or Old Gas
Exmark offers gas, diesel, and propane-powered lawn mowers. If you have a gas-powered Exmark mower, you need to make sure you are using the correct gas.
There are so many different types of fuel offered at gas stations today. It’s easy to get confused by all of the options.
Buying the right fuel is essential to protecting your fuel system and engine. Exmark lawn mowers, other than diesel and propane models, require unleaded gasoline that has an octane rating of 87 or greater and an ethanol content of 10% or less.
Using the wrong fuel type or fuel containing high levels of ethanol can cause your Exmark not to start. Worse yet, it can cause significant engine damage.
Always read the labels on your fuel pump carefully to know what is in the fuel you are buying. I go over the best type of fuels to use in your Exmark in “This is the Gas to Use in Your Exmark Mower”.
Use Fresh Gasoline
Many people don’t realize gas only has a shelf life of about 30 days before it starts to break down and lose its effectiveness. The use of ethanol in your gasoline attracts moisture which is not good for your fuel system.
When the ethanol and water run through your fuel system, it can cause the mower to run sluggish and cause a gummy buildup that restricts fuel flow to your Exmark’s engine.
Repair: Drain and flush the fuel tank. Add fresh gasoline that includes a fuel additive to stabilize and clean your fuel system like Sea Foam. Read more about the advantages of using Sea Foam Motor Treatment in your Exmark.
Gas Cap Won’t Vent
Your Exmark gas cap is designed to vent allowing air to pass through the cap. When air is unable to enter through the vent, your gas tank will form a vacuum. This vacuum restricts fuel from leaving your gas tank. Without fuel flow, your Exmark won’t start.
You may be able to identify if your gas cap is clogged by removing the cap and running your mower. If your mower starts and runs fine, replace the fuel cap to check whether it will starve your mower of fuel because your cap does not vent.
If your mower shuts off after letting it run for a while, there is a good chance your cap could be bad.
Repair: When the cap doesn’t vent, I typically replace my fuel cap with a new Exmark cap. You can try to clean your cap to get it to vent first. If that doesn’t work, you need to buy a new cap.
Bad Spark Plug or Loose Connection
You need to have spark for your Exmark to start. Check your spark plug wires and make sure they are securely connected.
Remove your spark plugs and check the tips for carbon buildup. When the tips are dirty or the spark plug has a burnt electrode or damaged porcelain they can fail to work properly.
You will also want to check your spark plugs for damage and ensure they are gapped correctly to avoid starting problems.
Repair: Remove your spark plug and inspect it for signs of carbon buildup or cracked porcelain insulator. Replace with a new spark plug(s). Make sure they are correctly gapped and the spark plug wires are secure.
Clogged Air Filter
A clean air filter is necessary for your engine to run. The engine pulls clean air through the air filter.
When the filter is plugged with grass and dirt, the engine cannot get the air it requires and can overheat and shut down. Running a dirty air filter or no filter at all is putting your Exmark engine at risk of serious damage.
Minimize starting, run ability, and internal damage problems by periodically checking your air filter’s condition.
Clean your air filter or replace it when it is too dirty to clean. You will have to replace your air filter more often when you are mowing in dry dusty conditions.
Repair: Check your paper air filter by removing it from the air filter housing. You will find your Exmark air filter cover attached by clips or thumbscrews. Remove the cap and filter.
Be careful to not knock any dirt into the air intake when you remove the air filter. Wipe any remaining dirt in the housing with a dry cloth.
Tap your filter against a solid surface to loosen the dirt and knock it out of your filter. Once you have removed the loose dirt, hold your air filter up to a light source.
If you see light shining through the paper element, you are good to reuse the filter. If you don’t, you must replace your filter with a new one.
Bad Fuel Pump
Exmark mowers use a fuel pump that may eventually go bad. Old gas sitting in your fuel pump can degrade plastic and corrode the internal components of the fuel pump over time.
This will cause your fuel pump to fail to build the pressure it requires to push fuel to the carburetor. You may notice fuel leaking from the seams of the pump indicating you need to replace your fuel pump.
If you don’t physically view damage or leaking, test your pump to check if it is still operating properly. Start by verifying you have a flow to the fuel pump by using the shut-off valve or clamps to start and stop fuel flow.
Once you have verified you are getting flow to the pump, you need to check to make sure fuel is being pumped out of the fuel pump.
Do this by disconnecting the fuel hose from the carburetor and placing it in a container. Start your mower and watch the hose for a constant or pulsating fuel flow.
Repair: Replace your fuel pump if you are not receiving a constant or pulsating flow out of the pump.
Plugged Fuel Filter
I replace my fuel filter at least once a year to make sure I’m running a good filter and don’t have to worry about it becoming an issue. It is the least expensive filter on your lawn mower.
The function of a fuel filter is to filter out dirt and other debris that may have gotten into the fuel tank. A filter can become clogged with dirt or gummed up by old fuel.
Repair: A clogged fuel filter must be replaced with a new one. Make sure you install it correctly with the fuel flow following the arrow on your fuel filter.
Blockage in the Fuel Line
If you haven’t realized a common theme yet, you will. Bad or old fuel can cause clogging and damage throughout your fuel system. This includes the fuel lines as well.
You may not visibly see a clog in your fuel lines so you’ll have to check your hose by starting and stopping fuel flow using the fuel shut-off valve located under your fuel tank.
If you don’t have a shut-off valve, just use a clamp on your fuel line to start and stop the flow. With your fuel flow stopped, remove one end of the fuel hose and place it into a container.
Start your fuel flow and check for fuel coming out of the hose you placed in the container.
When checking the fuel hose between the fuel tank and the fuel pump, make sure the container you place the hose in is lower than the fuel tank when checking for flow so gravity can do its job.
Repair: Once you find a clogged line, try to remove the blockage. Do this by removing the line from your Exmark.
Spray carburetor cleaner into the tube to try to loosen the blockage. Then use compressed air to blow air into the line to blow out the clog. If you are unable to dislodge the clog, you will need to replace your fuel line.
You can purchase a mower fuel line at your local hardware store or online. I do recommend replacing your fuel lines when they are dry and beginning to crack even if you don’t find a clog in them.
Clogged & Dirty Carburetor
It is common for a carburetor in your Exmark to become dirty and clogged from running old fuel and fuels containing ethanol. The function of your carburetor is to regulate the mixture of gas and air required to create combustion in the engine’s cylinder.
When your carburetor is gummed up, your engine won’t get the fuel and air it needs to start. A dirty carburetor will need to be cleaned and any failed components must be replaced.
Repair: If you are a little mechanical you should be able to handle disassembling the small parts in your carburetor to clean your Exmark’s carburetor.
If you are unsure about cleaning your own carburetor, you can have your local small engine mechanic clean your carburetor or you can replace it with a new carburetor.
Clean the carburetor by taking it apart and using a carb cleaner to clean it. You can find steps for cleaning your carburetor here. If your carburetor is too dirty to clean adequately, you should replace it.
Bad Battery, Loose Cables, or Corroded Terminals
Your Exmark will not start with a bad battery, loose cables, or corroded terminals. Confirm your battery terminals are not corroded and are attached securely to the battery.
Repair: Clean corroded terminals in a baking soda solution containing 2 cups of water and 3 rounded tablespoons of baking soda. Use a wire brush to scrub the terminals clean.
Test your battery with a multimeter. You need a reading of about 12.7 volts. Place on a charger to charge your battery if your reading is less than this.
Read more about the steps and items needed to charge your battery here. If your Exmark battery does not hold a charge, you will need to replace it with a new battery.
Bad Safety Switch
Your Exmark lawn mower uses several safety switches designed to keep the operator safe. The manufacturer installs safety switches to prevent your mower from starting without your parking brake being engaged.
It also has a safety switch that disengages your mower deck and shuts off your mower if it no longer senses the operator is present. You may have additional safety switches on your Exmark. When these switches fail, your Exmark mower will not start.
Repair: Test an Exmark switch using a multimeter. You can temporarily bypass the safety switch to identify a bad switch but only do this for troubleshooting purposes.
Never operate a mower without the safety switch. Never run a mower when a safety switch is bypassed. A safety switch can save you from serious injury and you never know when you’re going to need it.
Bad Ignition Switch
You insert the key into your ignition switch and turn it only to find your Exmark doesn’t start or even turn over. The ignition switch could be the problem.
Repair: You can use a multimeter to test the ignition switch. Replace the switch if bad. After you have checked your spark plug is working, check the continuity of your ignition coil using a multimeter.
Bad Starter Solenoid
An Exmark mower solenoid is an electromagnetic switch that is like an on-off switch that actuates the starter motor to turn over the engine.
A click or hum when turning your ignition key is an indication to check your solenoid. Another indication your Exmark mower solenoid may be bad is when a wire attached to your solenoid gets hot and begins to smoke or melt.
Repair: Test your Exmark mower solenoid by following the steps here. Replace your solenoid if it is found to be bad.
Faulty Charging System
While the charging system isn’t the main reason your Exmark mower won’t start, it can contribute to a weak battery that prevents the mower from starting.
When the charging system fails to charge the battery, the battery may not be able to start the mower the next time you go to use it.
A bad stator or alternator can be the problem along with several other electrical parts. Read this article to test your charging system here using an ohmmeter.
Repair: Have your local Exmark dealership or lawn mower small engine repair shop check your charging system to isolate the problem. If you don’t have experience with charging systems, you will most likely just be replacing electrical items until you find one that works.
This can get very expensive because most parts stores won’t let you return electrical parts if you find a part your purchased doesn’t resolve your starting problem.
Incorrect Exmark Operating Procedure
Exmark implements safety precautions with their lawn mowers that require certain steps to be followed when starting and operating the lawn mower.
Repair: Refer to your Exmark operating manual to ensure you are operating your lawn mower correctly so you don’t set off the safety features that shut off your lawn mower.
Still Having Problems with Your Exmark Lawn Mower?
I’ve put together a handy guide for the most common problems an Exmark owner will encounter. When you own a mower long enough, you are going to run into many different issues with your lawn mower.
Check out and bookmark this page to use as a reference when you need help with your mower: Common Exmark Lawn Mower Problems & Solutions