How to fix Gardenline lawn mower not starting?

I have a Gardenline essential lawn mower. It is not firing. This does not have a primer. I cleaned the caburator and tried . Still not working.. I think fuel is not injected into the chamber. In a machine without the primer how, how the fuel is injected for initial firing?

David

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MitchellMc

Welcome to the Bunnings Workshop community @dajeya. It's wonderful to have you join us, and many thanks for your question about starting a lawnmower.

A self-priming lawn mower typically uses a diaphragm carburettor to draw fuel from the tank into the engine without a primer bulb. When the starter cord is pulled, the engine creates suction, creating a vacuum in the carburettor. This vacuum pressure draws fuel from the tank through a fuel line, mixing it with air and delivering it to the engine for combustion, simplifying the starting process without the need for manual priming.

How old is the fuel in the tank? If it's been sitting there for more than a year, I'd replace it with fresh fuel. What does the sparkplug look like?

Please let me know if you have any questions.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/36772#Comment_36772

spark plug , the plug bout and the magneto are all new. I removed the carb and gave through cleaning.

in the first picture, what is the function of a black tube coming from the rotter to the air filter housing?

thanks

dajeya

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/80658#Comment_80658

And how old is the fuel @dajeya?

The black hose you're referring to is likely the breather hose. It's a component designed to allow air to flow into the carburettor or air filter housing to maintain proper air pressure within the system. This helps prevent vapour lock and ensures the smooth operation of the engine. If the breather hose becomes damaged or disconnected, it can lead to engine performance issues.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/104902#Comment_104902

Hi Mitchell, in the choke mode the butterfly valve is in closed position. The butterfly valve at the back of the carb is in open position. Which should be correct. Am I correct? What’s the function of the governor in the starting process? I don’t see any movement of the rod or spring . Please explain!

regards

dajeya

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/119550#Comment_119550

Hi @dajeya,

In the choke mode, the butterfly valve at the front of the carburetor should indeed be closed to restrict airflow, enriching the air-fuel mixture for easier starting, especially when the engine is cold. The butterfly valve at the back of the carburetor, often called the throttle valve, should be in a partially open position to allow a small amount of air to enter the engine.

As for the governor's function in the starting process, the governor typically doesn't directly affect the starting process or move. Instead, its primary function is to regulate engine speed to maintain a consistent and optimal operating RPM under varying load conditions. The governor achieves this by adjusting the throttle position in response to changes in load, ensuring the engine runs smoothly and efficiently. Once the engine starts and begins to operate at higher RPMs, the governor will start to regulate the throttle position to maintain the desired speed.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/128424#Comment_128424

Thanks Mitchell for highlighting that.

so why it’s stubborn to start? What else I should do?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/134136#Comment_134136

The first thing to verify when troubleshooting a mower is how old the fuel is @dajeya. How old is it?

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/137734#Comment_137734

Hi Mitchell, Not that old.

Dajeya

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/140188#Comment_140188

If it's within a year old, @dajeya, it should be fine. Anything older than a year, and I'd swap it out for fresh fuel.

Further testing would require a check for spark. If you are getting a spark but the fuel isn't wetting the plug, you'd likely need to take it to a service centre and have a technician look it over for you.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/141933#Comment_141933

Hi Mitchell, thanks for your suggestion, take it to a mower tech. Do you know how much they charge? Not less than $150. Why I should I take the trouble in carting and paying so much. I can buy a new one. I decided to throw it. Thanks for the discussion.

dajeva

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/143224#Comment_143224

That's understandable, @dajeya. I do apologise, but you've now gone through all basic troubleshooting, including an advanced step of cleaning the carburettor. At this point, you'd be looking at replacing parts in the hopes that it would resolve the issue and that in itself can be a costly exercise.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/141933#Comment_141933

Hi Mitchell,

This machine does not have a primer to inject fuel to start the machine. How can it start when you pull the starter rope? Is there a automatic choke which inject the fuel when you pull the cord? if so where is it?

When I physically inject a little fuel into the carb through the air filter and start, it starts with 2 pull.

dajeya

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/143228#Comment_143228

Hi @dajeya,

A lawn mower without a priming bulb typically uses a gravity-fed fuel system or a diaphragm carburettor to inject fuel into the combustion chamber for the initial ignition. In both systems, the engine's mechanical action, such as pulling the starter cord, creates suction that draws fuel from the fuel tank into the carburettor and then into the combustion chamber, enabling the engine to start.

A blockage in the fuel or return lines could prevent the fuel from being drawn to the carburettor.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/144171#Comment_144171

Hi Mitchell,

My carb is not a diaphragm type. If there is a blockage in the fuel line, the machine will not keep running once it starts running. How suction is created to pump fuel into the carb when you pull the cord? What is the mechanism here? What is the function of the black tube that is running from the rotter to the air filter housing?

dajeya

IMG_6564 (002).jpg

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/144870#Comment_144870

In a lawn mower with a non-diaphragm carburettor, the suction needed to pump fuel into the carburettor when starting is generated by the engine's intake stroke. When you pull the starter cord, the engine's piston moves downward, creating a vacuum in the combustion chamber. This vacuum draws air in through the carburettor, which in turn draws fuel from the fuel tank through the fuel line and into the carburettor.

The black tube running from the carburettor to the air filter housing is likely the crankcase breather tube. Its function is to vent gases from the engine's crankcase, allowing them to be drawn into the carburettor and burned in the combustion chamber. This helps to prevent pressure buildup in the crankcase, which could lead to oil leaks or other issues. Additionally, it helps to reduce emissions by ensuring that any unburned gases are circulated back into the engine for combustion.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/145407#Comment_145407

Hi Mitchell,

Thanks for your reply. What you suggest is, there is insufficient vacuum created to draw air to get fuel into the carburetor to start first. What is the solution please?

Regards

dajeya

DIYGnome

https://www.workshop.bunnings.com.au/discussion/comment/145827#Comment_145827

@dajeya

If I read correctly, you stated if you manually placed fuel into the carburetor the mower fires up... thus you have a fuel delivery issue.

how is the fuel filter in the tank (they can become blocked)?
how are the fuel lines (fractured lines lose vacuum/pressure)?
how is the filter (a clogged air filter will stifle the combustion process)?
have you tried starting (normal process) with no air filter?

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/145827#Comment_145827

Hi @dajeya,

Some good suggestions from @DIYGnome on things to take a look at.

Let us know how you go.

Mitchell

dajeya

https://www.workshop.bunnings.com.au/discussion/comment/146147#Comment_146147

Hi Mitchell,

Yes I said, when I inject little fuel in the carb it fires.

There is no leakage in the fuel line, the air filter is clean. I removed the fuel tank and cleaned. If there is fuel block, then how it continues to run once it starts?

When I removed the carb for cleaning, I used carb cleaner at the fuel entry point and it was coming out with no blockage.

Now what to do?

Regards

dajeya

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/146422#Comment_146422

@dajeya,

If your lawn mower starts and then runs when manually injecting fuel but fails to auto-prime and start on its own, the issue likely lies in the carburettor's ability to draw fuel during the starting process. Despite cleaning the carburettor and ensuring no blockages in the fuel line or air filter, there might still be a problem with fuel delivery or carburettor function. Double-check the carburettor's jets, passages, and the functionality of the float and needle valve.

Mitchell

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