Man Removing Grass From Lawnmower

Why Won’t Your Lawnmower Start?

You press the power button on your lawnmower, expecting the familiar roar when it bursts into life. Instead, you hear a splutter, a whine or perhaps nothing at all.

Your lawnmower may be lifeless now, but starting it up could be quite simple. Follow our checklist of common faults to find your fix (ideally before your grass grows up past your knees).

Electric Lawnmower Not Starting?

If you’ve got an electric mower with a cord that you plug into the mains, there are five main issues that could be stopping it from starting.

Issue 1 – A problem with your lawnmower’s power supply

If something’s stopping the flow of electricity into your mower, it’s not going to start from the moment you take it out of your shed or garage.

Here’s what to check to fix a completely lifeless mower that’s not getting the power it needs to run.

– Plug another appliance into the same plug socket you used to try to start your mower. If that appliance doesn’t work either it’s likely it’s the socket itself that’s got an issue. Check your fuse box.
– Open up the plug of your mower and use a multimeter to check the fuse hasn’t blown. We’ve got a guide that teaches you how to use a multimeter if you’re not already familiar with the process.
– Have a look at your lawnmower cable. You may have accidentally sliced into it when you last mowed or it could have made a tasty treat for a hungry mouse whilst you stored your mower. Either way, if the cable’s worn or damaged you’ll need to replace it straight away to fix your mower and also avoid getting a nasty shock!

Issue 2 – Jammed blades

Did you hear a loud humming noise before your lawnmower cut out? Chances are your lawnmower blades could be blocked.

Build ups of dirt, grass or lawn debris can cause your blades to jam. There could even be something wrapped around them that’s stopping them from turning.

The solution is as simple as switching off and unplugging your lawnmower before thoroughly cleaning the underside. Make sure anything obstructing the blades is removed before switching your mower back on.

If your blades were jammed and your lawnmower is still not working after you’ve freed them, this could be down to the thermal cut out.

Issue 3 – Thermal Cut-Out Activated

The thermal cut out protects the motor in your lawnmower from overheating. It could activate if your lawnmower is working too hard, for example, if you’re cutting really thick or long grass or if the blades get jammed or obstructed.

Luckily, this issue is easy to resolve, by doing one of two things.
1) Do nothing! Usually, once your mower cools down the thermal cut out will reset on its own.
2) If it doesn’t reset you can reset it. Check the manual to find out how. Lost your manual? If we’ve got it in our manual database you can download a PDF copy.

Issue 4 – Faulty On/Off Switch

If your lawnmower runs fine once it gets going but is increasingly difficult to start, this could point to a problem with your on/off switch.

Once you’ve investigated with your trusty multimeter and found a faulty switch is to blame for your issues, fitting a replacement is straightforward.

– Unplug your mower.
– Remove the switch casing from the lawnmower.
– Undo the screws holding the casing together to access the switch.
– Take a photo of the wires attached to the switch to help you reconnect them.
– Disconnect the wires from the switch (using pliers if necessary).
– Connect the wires to your replacement switch in the same order.
– Reverse the steps above to reassemble your lawnmower.

Watch Josh take you through the repair step-by-step.

You’ll need to know the model number of your lawnmower to get the right replacement switch for your model. See our model number finder to help you locate it.

Issue 5 – Faulty Motor

Still having problems starting your lawnmower, even after checking the common issues above? In this case, the motor itself could be faulty. Replacing a lawnmower motor may sound complex, but it’s really not as hard as it may sound.

Watch Helen replacing this Flymo motor and you’ll see that there’s no reason why you can’t have a go at fixing your lawnmower yourself!

Petrol Lawnmower Not Starting?

Petrol lawnmowers don’t have any problems with plugs or electric power cables because they don’t have them!

However, there are different starting issues that may affect your petrol mower instead.

Issue 1 – No fuel

Yes, this solution sounds far too obvious. However, there are people out there who ignore the petrol light on their car for so long they actually end up stranded miles from the nearest pump. So we don’t think it’s unreasonable to suggest that the first thing you do is check that there’s fuel in your mower. Just in case.

Issue 2 – Dirty or evaporated fuel

All throughout the winter months, whilst you’ve been enjoying cosy nights in, your mower has been sitting idle. Over this time it’s quite possible that dirt or dust has got into the fuel tank or that the combustible parts of the fuel have evaporated.

Ideally, you should use up or empty the fuel in your mower before you store it away and fill it up with fresh petrol at the beginning of the new mowing season.

But right now, if you’ve got stale fuel in your tank that’s stopping your lawnmower starting, you’ll need to drain it. Empty the main fuel reservoir into a bowl by uncoupling the fuel line. Then press the release valve on the carburettor (if fitted), to drain this area too.

Once you’ve got rid of the old fuel, you can top up your mower with fresh new petrol.

Issue 3 – Fuel valve closed

Closing the fuel valve when you’re storing your lawnmower is a good idea. The valve keeps the petrol secure in the tank and stops it from leaking out or getting into the engine when you don’t want it to.

However, if you’ve closed the valve and you’re trying to start your mower, you’re not going to get very far! Check that the fuel valve is open and set to the position that allows fuel to get to the engine and you’ll have a much more successful mowing experience.

Issue 4 – Faulty spark plugs

Your petrol lawnmower needs a spark to ignite the fuel inside it and roar into life. This spark comes courtesy of the spark plugs so if they’re dirty or excessively worn that can stop your mower from starting.

To clean your spark plugs:
– Remove the plugs
– Clean them with a wire brush
– Buff the area between the two electrodes with fine sandpaper

If cleaning the spark plugs doesn’t fix your problem, replace them instead. Find the right plugs for your model, fit them in the place of your old ones and your lawnmower will be good to go.

Issue 5 – Blocked carburettor

None of the above issues apply? A blocked carburettor could be to blame for your lifeless lawnmower.

The carburettor is a part in your lawnmower engine that mixes air with fuel to help it burn. You can try using a bit of carburettor cleaner to flush out any blockages but if this doesn’t work or there are parts that look corroded, replacing the carburettor is the best bet.

For more handy advice on what to look for if your petrol lawnmower won’t start, see our video:

How to Avoid Problems in Future

It’s always easier (and cheaper) to prevent problems rather than curing them. This five-step maintenance check will help reduce the risk of faults occurring in your mower in future.

1. Check the lawnmower blades are sharp so they’re not damaging your lawn or overworking the motor.
2. Clean the underside of the mower to stop blades from getting stuck.
3. Rub moving parts with an oily rag to prevent rusting.
4. Ensure the air vent are clear to allow proper ventilation in your mower.
5. Tighten any loose screws or connectors and if they’re worn, replace them.

We hope that with this advice you can keep your lawnmower reliable throughout the mowing season. Enjoy your freshly mown grass!


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