Lawn Mower Starts Then Dies: Solved! (2023)

It’s not uncommon to run into a stalled lawnmower motor, and many mower owners have likely faced this problem. So, if you’re experiencing a lawnmower that starts but then dies, here’s what you need to know.

In this section, we’ll discuss the most frequent problems that can cause your lawnmower to start up but then stall and shut down. We’ll provide you with practical tips and guidance on how to address these issues effectively.

What Is the Most Common Lawnmower Issue?

It’s not uncommon to experience stalling lawnmowers. However, one particular issue stands out as the most prevalent. If you find that your lawnmower starts up but then suddenly stalls, chances are high that the carburetor is to blame.

If your lawnmower starts but then stalls out and dies, the culprit might be a dirty carburetor. It’s a common issue that many people face. Understanding how a dirty carburetor can cause this problem is crucial.

A Dirty Carburetor Can Cause a Lawnmower To Start Then Die

A dirty carburetor is the main culprit behind a stalled motor. Its primary function is to mix air with fuel to ignite the engine. Although gasoline itself is not highly flammable, it becomes combustible when mixed with air. This fact is contrary to what movies might lead us to believe.

When your carburetor becomes dirty, its ability to mix air and fuel in the correct ratio is compromised. As a result, the gas won’t combust properly, causing your engine to sputter and not perform at its best. Essentially, the carburetor draws air from the surrounding environment and combines it with fuel in the correct proportion, so if it’s not functioning correctly, your engine won’t kick into gear as smoothly as it should.

If your motor starts but won’t stay running, it could be due to a dirty carburetor. Look out for a few telltale signs, such as getting a good initial injection of gas from the primer bulb, followed by the carburetor failing to get enough oxygen to keep combusting.

If you find that your carburetor is clogged, it is probably due to evaporated gas that has blocked the pores. Over time, gas left in the tank will evaporate, leaving behind ethanol which can settle in the carburetor’s air channels. This can cause the evaporated gas to condense inside the carburetor, resulting in a malfunctioning mower. Fortunately, most cases can be resolved by cleaning and resetting the carburetor, which will allow your mower to run smoothly once again.

To fix your carburetor, the best approach is to remove and clean it. You’ll require a few tools to do this effectively.

    • Sockets and a ratchet: You will need a socket wrench to remove the carb. Consult your owner’s manual to figure out what size socket you need. 
    • Gas siphon: A gas siphon will remove any excess gas and oil from your engine. A good gas and oil siphon can save you a lot of time instead of manually draining the tank and oil repository. 
    • Carb cleaner solution: You can use rubbing alcohol to dissolve any dried and gummed-out gas, but it is probably a better idea to get a can of carburetor cleaner. This aerosol can have a directional straw and is designed specifically to dissolve the gas residue. 
    • Fuel treatment solution: While not necessary, a fuel treatment solution can improve your engine health and keep gas from drying out and gumming -up your carb in the future. You can buy both a carb cleaning solution and fuel treatment solution from your local home & garden store. 

How To Clean a Dirty Lawnmower Carburetor

If you want to clean your lawnmower’s carburetor, then you can easily do it by following these steps.

1. Inspect the Air Filter

Start by checking the air filter to see if it’s dirty. If it is, remove the debris and grime buildup, and your carburetor should be able to function effectively once again. An indication that the air filter may be dirty is if you notice black smoke emanating from the exhaust.

2.  Check the Connections

Once you have ruled out the air filter as the cause of the issue, it’s time to inspect the connections. Dirty connectors between the throttle and choke plates can become sticky, while constant vibration can wear down screws. If the screws are stripped beyond repair, replacing the entire carb may be necessary.

3. Clean the Carburetor

If the issue is not with the connectors, then the next step would be to remove the carburetor and clean it thoroughly. Gently detach the choke and throttle linkages from the lever and slide the carburetor off its mounting bolts. You may need to unscrew some parts to disassemble the entire carburetor. Remove the primer from the base and take out the metering plate and gasket. With the internal components now exposed, use a carb cleaning solution to spray the inside of the ports and remove any residue. Once you’re done, wipe down the carburetor with a soft cloth to give it a thorough cleaning.

4. Examine the Carburetor’s Fuel Bowl

Don’t forget to inspect the carburetor bowl too. This component holds a small amount of fuel that is necessary to keep the engine running. As time goes by, the fuel bowl gathers old gas which will eventually evaporate and leave behind a buildup. You can easily locate the fuel bowl as it is positioned behind the air filter and has a unique bowl shape. Be sure to include this in your maintenance routine.

5. Clean Off any Rust

If you notice rust built-up on your carburetor, it is essential to take action and clean it off. Sandpaper can be used to effectively remove the rust buildup and restore your carburetor to its optimal condition.

6. Reassemble the Carburetor

After cleaning all the components thoroughly, it’s time to put the carburetor back together and reattach it. Be sure to double-check that all the diaphragms, gaskets, metering plates, and primer are properly attached before putting it back on the engine. If any of these parts are not properly attached, you may still encounter the same issue of the engine starting and then sputtering out.

7. Reattach Everything and Fire Up the Lawnmower

After reattaching the carburetor, reinsert the fuel line and reinstall the air filter housing. Once all components are back in place, add gasoline to your lawnmower and give it a try to test if the problem has been resolved.

If your lawnmower is still experiencing problems related to the carburetor, make sure all the components have been reconnected correctly. If the issue persists, consider replacing the old carb with a new one.

How To Stop Your Lawnmower Carburetor From Clogging

To avoid a clogged carburetor, it’s best to clean it regularly by removing it and giving it a thorough cleaning. It’s recommended to clean your carburetor after every few uses or if you’ve stored your mower for a prolonged period. By doing so, you can keep your carburetor in top condition and prolong the life of your mower.

If you want to avoid clogging while mowing your lawn, investing in a high-quality mower is a smart choice. Briggs and Stratton is a reputable brand that offers lawnmowers made of top-notch components that are resistant to rusting and gumming up due to dried gasoline.

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