How To Start A Petrol Lawnmower

Learn how to start a petrol lawn mower effortlessly using our easy-to-follow guide with photos of each step.
Written By: Archie Rich | Updated:
How To Start A Petrol Lawnmower
Archie Rich/DIY Works

Whether you have a Hyundai, Mountfield, Murray, Cobra or any other type of petrol lawnmower, the majority will start up using the same technique.

However, if you are new to the world of petrol lawnmowers, trying to get it to start the first time or at all may be something that you are struggling with.

To ensure you have the best chance of starting a petrol lawnmower the first time, we’ve created the guide below that covers each step.

How To Start A Petrol Lawnmower

1. Check The Oil & Petrol

As you would do with a car, it’s crucial that you check the fluids beforehand.

However, unlike a car, there are no warning lights that’ll appear if the lawnmower is low, which means that you’ll need to do this manually before starting the engine.

To check the oil in your lawnmower, you’ll want to pull the dipstick out and clean it off with a tissue before putting it back into the tank. You can then proceed to take it out and check to see if the oil is between the minimum and maximum marks of the dipstick. If it isn’t, you’ll want to top it up if required or replace it if it’s old oil (over a year old).

In terms of adding petrol to the lawnmower, it’s advised to top it up while it is cold. Ideally, you’ll want to use fresh unleaded petrol that isn’t too old or has been left outside in direct sunlight.

2. Prime The Engine

After checking the fluids, you can proceed to start your petrol lawnmower.

To begin, you’ll need to prime your engine using the primer bulb that’s usually located on the side of the engine and in a distinctive colour, such as red (as shown in the image).

To prime the engine, you’ll need to press the bulb 3 to 4 times.

how to start petrol lawnmower

Archie Rich/DIY Works

It’s important to note that many premium petrol lawnmowers don’t require priming to start the engine, so they won’t have a primer bulb. Therefore, if there is no primer bulb, you can skip this step and move on to starting your petrol lawnmower.

3. Pull The Lever Towards The Handle

With the engine primed, you’ll want to pull back the safety lever, allowing you to start the engine.

Depending upon the model of petrol lawnmower you own, you may have two levers where one is the safety lever and the other is used for self-propelling the machine. Usually, the top lever is the safety lever, which you’ll need to hold down to start a petrol lawnmower.

how to start a petrol mower

Archie Rich/DIY Works

The levers themselves should move freely, and you shouldn’t need any force to hold them. However, if you find there is a slight resistance, spray WD40 on the joints.

4. Grip & Pull The Cord

Whilst holding the safety lever in place (some models don’t need holding), get a firm grip on the pull cord handle and then sharply pull it. If the engine is cold, you may need to pull the cord 3 to 4 times, but if the engine is warm, it should start up upon the first pull.

If your petrol lawnmower won’t start, please read our advice further below.

how to start a petrol lawn mower

Archie Rich/DIY Works

5. Self-Propel Activation

If you have a lawnmower that self-propels, with the engine running, you can pull the lever upwards to activate the forward motion. This will push either the front or rear wheels and make pushing the lawnmower up inclines far easier.

However, it’s important to note that you don’t have to use it all the time, and it’s not required to start a petrol lawnmower. It’s simply an optional extra added to many lawnmowers that’s very useful for large lawns with steep inclines.

Why Won’t My Petrol Lawnmower Start?

If you’ve followed our guide on starting a petrol lawnmower and were unsuccessful, you may have a problem. Below are some of the main causes of a petrol machine that won’t start:

  • Old or not enough petrol in the fuel tank
  • Blocked blades that can’t spin (the pull cord would be hard to pull if this was the case)
  • The spark plug isn’t tightly screwed in
  • The engine hasn’t been primed enough (you may need to press the primer bulb more than 3 to 4 times)
  • The air filter is dirty, clogged or damaged
  • The safety lever cable isn’t connected to the engine


Although a petrol lawnmower requires more effort to start, the benefits far outweigh the effort involved to start it. In our guide, we used a Mountfield machine, but the process of starting a petrol lawn mower is very similar to that of most models.

To ensure that your lawnmower’s engine is reliable and starts up every time, it’s important that you correctly maintain it. We wrote a guide on how to service a petrol lawnmower where we cover everything that you need to know.

If you require further information regarding starting a petrol lawnmower, feel free to get in touch, and we will try to provide our assistance where possible.

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