A Beginner’s Guide To Filling A Lawn Mower Petrol Tank

Whether it’s been a few years since you’ve used a petrol mower or this is your first time using this type of mower, you might need to familiarise yourself with the process of filling or topping up the fuel.


I’ve been using petrol mowers for over a decade now, so it’s safe to say I’ve done plenty of fuelling up over the years. Here, I’ve shared my step-by-step guide to expertly refilling your petrol lawn mower’s fuel tank. It’s pretty simple – you’ll have it mastered from your first go.

✅Key Takeaways:

  • Before you add fuel to your petrol lawn mower, wait for the mower engine to go cold, then check that you have the right fuel and gather your equipment, including the petrol, spill kit, and funnel or spout.

  • Next, unscrew the petrol tank cap, insert the funnel, and slowly pour petrol into the tank until it’s almost full.

  • Remove the funnel and replace the cap. The mower is now ready to be used.

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🤷‍♂️ How To Know If A Petrol Lawn Mower Needs Fuel

There are a couple of ways to know whether or not your petrol mower needs a fuel top-up:

  1. Check inside the tank. This is the most obvious way to determine the fuel levels in most mowers. Unscrew the fuel tank cap and take a look inside. If the fuel level seems low or you can’t see fuel at all, you know it’s time for a top-up!

  2. Check the tank’s gauge. Some petrol mowers have gauges on the outside of the tank that tell you roughly how much fuel is left. If your mower has this feature, simply check the gauge and top up the fuel if it says the petrol is running low.

Failed to check your mower’s fuel levels for a while? There’s a potential that the petrol tank might run out completely while you’re mowing. This has happened to me before, and, while annoying, it’s nothing to worry about. If your tank runs out, the mower’s engine will sputter to a stop, and you’ll have to refill the fuel system before you can get started again.

📑 How To Fill A Lawn Mower Petrol Tank: Step-By-Step Guide

Find out how to fill a lawn mower fuel tank in 7 easy steps below.

Step 1: Let The Mower Engine Go Cold

First things first, before you start the filling process, make sure your mower’s engine is cool. If you’ve just finished mowing your lawn, leave the mower in a well-ventilated area for at least 30 minutes to allow the engine to cool down. You don’t want to mess with a hot engine; adding fuel while the engine is still hot increases the risk of sparks and fire.


Step 2: Check That You Have The Correct Fuel

Next, check your mower’s user manual to ensure you’re using the right type of fuel. It may sound like a no-brainer, but you’d be surprised how easy it is to mix things up! Most petrol mowers run on regular unleaded petrol, but some might require a blend of petrol and oil, known as 2-stroke petrol. Using the correct fuel is essential to keep your mower running like it should, so if in doubt, see what the manufacturer’s saying.


Step 3: Prepare Your Fuel Spillage Kit

If you don’t have a spill kit, I recommend getting your hands on one since fuel spillages are a possibility with any fuel-using equipment, including lawn mowers. Spill kits contain the correct liquid-absorbing materials for safely mopping up petrol spillages. You can buy them online – we have one that’s years old, but this BearTOOLS Eco Spill Control Kit has good ratings on Amazon.


Step 4: Gather Your Equipment

Place your fuel container on a solid surface near your mower, put your spillage kit nearby in case you need it, and grab your fuel funnel or spout for the filling process. It’s much easier to use a funnel or spout than simply pouring the fuel directly from a container, which increases the likelihood of messy spills. We use this Draper Flexible Plastic Funnel.


Step 5: Unscrew The Petrol Cap

Locate the petrol tank cap, usually near the top of the mower’s engine. Unscrew it carefully and set it aside. You’re now ready to start filling!


Step 6: Add The Fuel

Position the end of the funnel inside the fuel tank opening and gently pour the petrol into the tank. Take it slow to avoid spills or overfilling. Keep an eye on the fuel level and don’t fill it to the very top – it’s best to stop when it’s about an inch or so from the top. That gives the fuel some room to expand as it warms up.


Step 7: Remove The Funnel And Return The Cap

Finally, once the tank is full of fuel, remove the funnel and place it on a cloth, then return the cap and screw it tightly in place. And that’s all there is to it! It’s just as easy to add fuel to a lawn mower as it is to refill your car.

refuel, mower, fuel, tank,

🏁 Final Word

I wrote this article because I wanted to provide a simple how-to guide for refilling a petrol lawn mower, and I felt that the other guides were too vague or lacked important information. Hopefully, I’ve answered all the questions you had about filling your mower’s fuel tank – but if I haven’t, you might find the answer you’re looking for in the FAQ section below.


Is it dangerous to allow a mower’s petrol tank to run out of fuel?

No, allowing the petrol in your lawn mower to run out isn’t dangerous. At most, it’s simply an inconvenience – no fuel in the fuel tank means the mower will stop running, and you’ll have to delay your mowing duties to refill the tank before you can restart the engine. But it won’t damage the mower’s engine.


Do you put straight petrol in a lawn mower?

You should only put straight petrol (4-stroke petrol) in your lawn mower if it has a 4-stroke engine. Otherwise, if your mower has a 2-stroke engine, it needs filling with 2-stroke petrol, which is a combination of petrol and 2-stroke oil. Adding straight petrol to a 2-stroke mower engine will cause the remaining oil to become quickly depleted, resulting in engine overheating.


Can you fill up a lawn mower at a petrol station?

No, it’s generally not recommended to fill up a lawn mower at a petrol station in the UK. What you can do is fill up a suitable container with fuel and take it back home with you to fill your mower. Make sure to check container filling restrictions at your local fuel station and be aware of UK laws, which state that you can store no more than 30 litres of petrol in containers.


Should I drain the petrol from my lawn mower before adding more?

No, generally, you don’t need to drain the petrol from your lawn mower before you add more, as long as you’re using the mower – and therefore the fuel – regularly. However, if you plan to store the mower for longer than a couple of weeks without using it, I recommend draining the fuel before you next refill it because petrol goes stale and loses its volatility in around 30 days. I’m going to be completely honest here: in my time as a greenkeeper, I’ve hardly ever drained the fuel from any mower I’ve used, and I’ve never had any operational issues.


Should you store lawn mower with full tank of petrol?

Yes, there’s no problem with storing your mower with a full tank of petrol if you’re using the mower regularly (aka throughout the grass growing season). But I recommend draining your mower’s petrol tank before storing it over winter because petrol has a limited shelf-life and degrades over time. If you choose to leave the petrol in the tank, you’ll struggle to start the mower’s engine come spring.


Can you put too much petrol in a lawn mower?

No, you can’t technically put too much petrol in a lawn mower. In most lawn mowers, you can fill the tank as high as you want without leaking. If you do accidentally add too much petrol, it’ll just overflow out of the fuel tank. You can use your fuel spillage kit to mop up the overflow.