How to Start a Lawnmower without Primer Bulb, step by step


Are you having problems with your walk-behind lawnmower not starting? You should probably consider pressing that primer bulb that sends fuel into your carburetor. But what if your primer bulb is not working correctly? How can you start your lawnmower? Luckily there is a method to start your mower without a primer bulb.

How to start a lawnmower without primer bulb, step by step:

  • Step 1: Prep your mower, check if the fuel tank is full, and secure the carburetor connections.
  • Step 2: Remove the air filter assembly to expose the engine’s air intake.
  • Step 3: Add a little spray of starter fluid into the air intake.
  • Step 4: Quickly reassemble the air filter assembly without letting the starter fluid dry.
  • Step 5: Start your engine by pulling the rope.
How to Start a Lawnmower without Primer Bulb, step by step 1

Lawnmowers and other small engine devices use a small and built carburetor compared to those used in automobiles. Carburetors in small engines do not have a high fuel storage capacity and rely on the primer bulb that sucks the fuel from the tank.

If your carburetor bowl runs out of fuel, you press the primer bulb to prime the engine by filling the carburetor with fresh gas. This step helps in starting the engine effectively. But when your primer bulb gets damaged, you encounter problems while starting. In such cases, you need to prime manually.

We suggest that you keep reading this article to get further insight into starting a lawnmower without the primer bulb.

Starting a lawnmower without primer bulb, step-by-step:

If you haven’t heard of it before, there exists a way to prime your lawnmower by employing a starter fluid. It may seem unlikely, but this method works.

Equipment needed:

Before making any repair or modification, it is always better to know about the type of gear you might need. However, for this modification, all that is needed is starter fluid and a flat head screwdriver, and you are good to go.

Important things to consider:

Although you might have guessed this procedure to be fairly straightforward, there are a few things that should be kept in mind before you proceed.

  • Priming time: Priming the mower engine without a primer bulb might take anywhere between 5 to 20 minutes, depending on how skilled you are. If you are accustomed to performing lawnmower repairs before, then it may not take more than 5 minutes for you.
  • Starter fluid: You need a starter fluid to perform the priming in this method. The fluid is a combination of chemicals that are fuel like and aid in starting the engine when the engine doesn’t prime.
  • Caution: Use the starter fluid with care and avoid spraying too much that might result in clogging and possibly affect the carburetor’s airflow.

Without further ado, we shall proceed towards the step-by-step demonstration of the procedure, which is the purpose of this article.

● Step 1. Make the initial preparations:

Before starting the engine, it is always better to prepare the lawnmower for the task. This step is about making sure that all the fuel lines and carburetor connections are correctly connected. Furthermore, the spark plug wire needs to be connected, and the spark plug should be in good shape. Also, check your fuel tank and see if there’s a need to add any fuel.

● Step 2. Locate and check the primer bulb:

Now, you need to locate and check the issue with the primer bulb. It is located right next to your carburetor. In some models, it might be situated underneath the carburetor. It usually has a red or black color.

Check your primer bulb and see if it is cracked or torn up. If it appears broken, then that is the reason it doesn’t operate. If it appears fine, press it three times as this causes the fuel to flow into the carburetor and initiate combustion.

– Pull the cord to prime the engine:

This is an optional step and can be performed to confirm if the engine starts with the bulb being bad or not. After you have pressed the primer bulb three times, push the throttle lever to the ‘choke’ position. Now, pull the cord at least three times to check if the engine starts or not.

● Step 3. Locate and remove the air filter:

If your engine didn’t start by following the steps mentioned above, you should consider priming it manually using starter fluid. But first, we should remove the air filter where the fluid has to be sprayed. We recommend taking pictures of the air filter assembly as this may help you keep track of individual parts so that you know where to fit them.

– Locate the air filter:

Locating the air filter is relatively straightforward. The air filter and its housing are situated externally on the side and can be removed easily.

– Remove the air filter:

Remove the air filter from the housing. Also, ensure that the filter assembly is detached entirely from the mower. Remove the nuts, screws, or any retaining pins that connect it to the mower’s body.

● Step 4. Spray the starter fluid:

Now, we shall proceed to spray the starter fluid into the air intake. This place is where the air cleaner was connected to the engine. Squirt a little starter fluid into the hole. Avoid spraying excessive fluid that might clog the jets and cause further problems.

● Step 5. Connect the air filter assembly back:

Now that the spraying is done, we are all set to initiate combustion, but first, the air filter housing and the filter needs to be connected back to the engine. You should proceed by carefully putting it back into the housing and securing it as necessary.

Now, this is very important for you to perform this step quickly. Otherwise, the starter fluid that partly comprises fuel might evaporate, and you might need to add it again.

● Step 6. Start the mower:

With the filter and its housing reassembled, it is high time for you to start the lawnmower’s engine as you usually do. Pull the cord with the throttle set to the highest position. It may not start at once, so give it a few tries. If the fluid hasn’t evaporated, it should start right away. If it doesn’t start, you might need to repeat the addition of the starter fluid. When the engine starts after the fluid spray, you have successfully primed it without using the primer bulb.

Related Questions:

1. How do primers work?

Primers are of two main types. Bulb and automatic primers. Both the types perform the same function, i.e., to supply the carburetor with fresh gasoline from the tank. However, their way of working is a little different.

– Bulb primer:

Bulb primers have a small rubber bulb on the outside whose function is to push the gasoline from the tank into the carburetor’s bowl. This fuel is fed to the engine for combustion.

– Automatic primer:

This primer draws fuel by creating a vacuum as the engine is turned on. When the engine is turned off, this primer retains the fuel in the carburetor so that next time when the engine starts, the carburetor has the necessary fuel to supply it for combustion.

Both the primers draw fuel from the tank to keep the carburetor full. If no fuel is present in your carburetor, then the primer might be faulty.

2. Why does a primer stop working?

Following are the reasons that can cause a primer to stop working.

– Cracked bulb:

This defect happens for bulb primers. The rubber bulb might get cracked or torn due to a sharp object such as iron nails or sharp stones. The torn bulb inhibits the flow of gasoline from the tank to the carburetor.

– Clogged fuel filter:

The primers draw fuel after it has passed from the fuel filter. Sometimes, the filter gets clogged due to fuel deposits generally resulting from old gasoline. Because of these deposits, the fuel doesn’t reach the primer in the first place and cannot perform its function.

– Cold primer:

Sometimes when the primer has been left standing for a while, there is a possibility that the fuel won’t be left in it anymore. In this situation, no fuel is left to feed into the engine for combustion. Hence, the engine won’t start in this condition.

3. Do all lawnmowers have a primer bulb?

Primer bulbs are a part of small engines. Generally, walk-behind lawnmowers employ small engines and have primer bulbs. On such engines, the carburetors are simplified in comparison with those used in automobiles. As a result, such carburetors have a rubber or plastic primer bulb to draw the fuel from the tank into the carburetor. This fuel is ultimately fed to the engine for combustion.

4. How do you start a lawnmower with primer?

To start a lawnmower with primer, you first need to check the fuel tank and see if more fuel needs to be added. Next, press the primer bulb at least three times to ensure that the fuel has entered the carburetor.

With that being done, push the throttle lever to the highest position. Now, start your engine by pulling the cord. If it doesn’t start after pulling the cord several times, then there is a problem with your primer.

Final Remarks:

To conclude, manual priming of an engine might seem like a complicated process, but it can be performed without much hassle. If you are a beginner at DIY repairs, then the step-by-step guideline offered by this blog post shall help fix your problem regarding primer bulbs. Furthermore, it is always helpful to equip yourself with the knowledge that aids you maintain and fix your devices on your own.

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