How to fix a lawnmower engine that won’t start

Approx Reading Time: 9 minutes

There is nothing as frustrating when you want to give your lawn a cut, and your lawnmower does not start. Not starting can be due to various reasons, and if you are not afraid to look at it yourself, you can save yourself some time and money. This article has broken down all the troubleshooting steps easily and will provide you tips and tricks related to engine maintenance.

How to fix a lawnmower engine that won’t start

  • Step 1: Open the fuel cap and check the fuel level that might be insufficient for the engine to start
  • Step 2: Clean the air filter from the dust and debris build-up
  • Step 3: Inspect the spark plug by checking if it’s dry or not
  • Step 4: Service the carburetor jets and bowl by removing all the debris deposits with the help of a carburetor cleaner
  • Step 5: Test the ignition system with an inline spark ignition tester

If you haven’t performed your lawnmower maintenance before or aren’t aware of where the mechanical components are located in your machine. Then keep reading this article as we unwrap this information for you.

Steps to Troubleshoot a Lawnmower that is Not Starting:

If a lawnmower does not start, it might be due to a variety of reasons that are explained below:

● Step 1: Fuel check

 As a thumb rule, to start your engine, you should pull the cord three times. If it doesn’t start after the third pull, then you have a problem. To troubleshoot this problem, it is a good idea to start from the absolute primary step. That is, to ensure if there is sufficient fuel in the gas tank. Open the cap of your fuel tank to check the fuel level, or maybe shake your mower from the side to hear the sloshing of the liquid. If the level is okay, then you need to move towards the next step.

● Step 2: Clean the air filter

After checking the fuel, the next step is to check the air filter by removing the screws securing its casing. The filter is usually dusty. It would help if you cleaned it by using compressed air or spraying it with an aerosol cleaner liquid. After it has been cleaned, try restarting your engine. If it doesn’t solve the issue, we then proceed towards checking the spark plug.

●  Step 3: Inspect the spark plug

First, to check the spark plug, remove the spark plug cable so that there is no chance for the engine to start accidentally. Now, try removing the spark plug by unscrewing it manually. Once it has come off, check if its end is dry or not. If the end is dry, then this points towards a fault in the carburetor. If it is wet and the engine still doesn’t start, you probably need to test the ignition system.

● Step 4: Service the carburetor

If the end of the spark plug was found dry in the above case, it meant a problem with the fuel transport to the engine, which occurs through the carburetor. Generally, gasoline becomes stale after it hasn’t been replaced after 30 days. As a result, it leaves deposits within the jets after it evaporates, eventually clogging those jets. The air-fuel mixture doesn’t enter the engine, due to which no combustion takes place. To unclog the carburetor, you should follow the steps below:

– Step 1: Unscrew the bowl

Before you clean the carburetor, make sure you dispose of all the fuel already present in the fuel tank. To view the carburetor, you first need to unscrew and remove the air filter. The fuel tank also needs to come off. After that, unscrew the bowl nut and remove the bowl along with its gaskets.

– Step 2: Clean the components

The nut that secures the bowl consists of the main fuel jet that is often clogged with deposits. You can use a carburetor cleaner liquid to clean the jet. Also, spray the bowl with the cleaner liquid and remove the sludge build-ups. Then, spray the carburetor cleaner on the float near the needle valve. If you have a compressed air gun, it might be a good idea to spray some compressed air on the carburetor center connected to the lawnmower body.

– Step 3: Assemble and maintain

After you’re done with cleaning, reassemble the carburetor components and add fresh fuel to the tank. The engine starts most probably. As a preventative measure, we always recommend that you should provide a fuel stabilizer to your fuel so that its quality doesn’t deteriorate over time. With the addition of a fuel stabilizer, gasoline can stay for up to 12 months in the engine without getting stale.

The servicing procedure is explained below in the video:

● Step 5: Test the ignition system

Referring to step 3 earlier, we stated that if your spark plug was wet, then the ignition system was tested. For this, we use an inline ignition tester to check for a spark.

– Step 1: Connect the ignition tester

There are two ends of an ignition tester, out of which one is connected to the spark plug wire. In contrast, the other is connected to the exhaust (as ground terminal). Now with the tester connected, you need to give three pulls to your stating cord and check if the tester is producing a spark or not. If no spark is produced, then it indicates a fault in your ignition coil.

– Step 2: Replace the spark plug

But if the spark is produced as it happens in most cases, then the ignition coil is fine and the only logical fault line now left is the spark plug. So, we recommend that you should replace the plug with an identical one for your engine.

Related Questions:

● 1: How do I start my lawnmower after winter?

– Step 1: Check the gasoline

If your lawnmower hasn’t been in use for a long time, then the first step you should do to start it is to check the gasoline and make sure you replenish it.

– Step 2: Pull the cord

Then, you need to prime the engine by pulling the cord three times at least. Turn the choke on and prime it again.

– Step 3: Tug the spark plug wire

Tug the spark plug wire to see if it’s loose or not. Pull it up if it’s loose. Then, inspect your spark plug and check if it’s worn out. If it is, remove it with a wrench and replace it with a new one.

– Step 4: Replenish the fuel

Drain out the used gasoline in your tank and dispose of it properly as s hazardous waste. Add fresh fuel into your tank and reprime the mower again. If you notice the gasoline smell becoming strong, stop repriming it for a few minutes. This smell indicates that the carburetor has been flooded with fuel at the moment.

● 2: How do you fix an electric lawnmower that won’t start?

– Step 1: Check the cable

Check the wires of the lawnmower and their connections. Make sure that the cable isn’t pulled out of its socket. In some cases, the cable is damaged at some points due to kinks and frequent use. In that case, it needs to be replaced.

– Step 2: Search for burnt fuses

It might be possible that the circuit breakers or fuses in your house just went out due to a power surge by the lawnmower. Under this condition, the lawnmower or any other socket won’t start until the fuse is replaced. To check that, you can connect a lamp to the socket and see if it turns on or not.

– Step 3: Empty the collecting bag

Some electric lawnmowers have a cutting bag located at the back, which collects all the cut grass. Once the bag reaches full capacity, the mower turns off. So, you should check if the bag is full and empty it if that’s the case.

– Step 4: Disable the safety feature

Some electric lawnmowers have a safety feature that prevents them from starting. The feature is there to prevent children from playing with the machine. If that’s the case, you need to press that button, which disables the safety feature.

– Step 5: Check the blades for obstruction

Electric lawnmowers don’t start if the blades have caught some grass, rock, or debris that prevents them from turning. In this case, you should carefully turn the mower over and remove the piles of obstruction in the blades that result in the lawnmower not starting.

● 3: How do I know if my lawnmower sparkplug is bad?

Following are the signs that indicate a faulty spark plug:

– Step 1: Hard to start

If the engine doesn’t seem to start after you continuously pull its cord, then chances are your spark plug needs to be changed. Typically, it should start after the first three pulls, but then the situation isn’t normal if that doesn’t happen.

– Step 2: Engine problems

If the engine stalls after starting or sputtering or missing, then it is one of the indications of a faulty spark plug.

– Step 3: Increased Fuel consumption

Suppose you notice that you’ve been using more fuel than normal during your mowing sessions. This consumption indicates that fuel isn’t being entirely burnt, due to which the fuel consumption increases. A bad spark plug causes this problem with low spark quality disrupting the combustion process.

– Step 4: Visual inspection

Spark plugs that appear damaged or broken with cracks need to be replaced immediately. The center electrode should have a flat top. If you see a rounded top, then it is a good idea to replace it. Suppose it appears good but has gasoline or carbon deposits on it. In that case, you need to clean the deposits and insert it again after cleaning.

Final Remarks:

In a nutshell, lawnmower engine problems originate primarily due to insufficient combustion in the engine linked with the debris build-up. These deposits are formed in components that deal with air-fuel mixtures, such as carburetors, filters, or spark plugs. To prevent such problems from occurring in the future, you should ensure that you clean these parts once a season. Furthermore, you should also make sure that you don’t keep the gasoline in the engine for more than 30 days, as it can result in deposits. If you do so, you should always add a fuel stabilizer to your tank. It is steps like these that not only ensure a longer service life but makes sure that your machine never lets you down.