Have you ever had this happen? Your mower sits for two months, and when you pull the starter cord, nothing happens. Or it runs fine, then suddenly dies and struggles to restart with no power. Most of the time, it’s not a broken engine – it’s a fuel system problem.
Petrol mowers are very sensitive to fuel quality. Especially with ethanol‑blended gasoline used in many regions – ethanol absorbs moisture from the air. Within a few months, the fuel separates, turns bad, and forms gum and sticky deposits that clog the carburettor, fuel lines, and filter. Instead of waiting for the mower to break down and paying for repairs, spend twenty minutes on a fuel tank cleaning and fuel management routine. Let’s go through it step by step.
Step 1: Safely drain the old fuel – don’t leave poison in the tank
If your mower has been sitting for more than 30 days, or you notice hard starting or rough idling, drain all the old fuel from the tank.
How to do it:
- Move the mower to a well‑ventilated area away from any flames or sparks.
- For a walk‑behind mower, use a siphon hose to draw fuel out through the filler neck. An easier way is to disconnect the fuel line (at the carburettor end) and let the old fuel drain into a suitable container. For ride‑on mowers, use a manual fuel pump.
- After draining, look at the fuel you’ve removed. If it looks dark, has layers, or smells like stale paint, it’s completely unusable.
- Don’t pour old fuel on the ground or down a drain – take it to a local waste oil collection point.
Important: Let the engine cool for at least half an hour before draining fuel, to avoid spilling petrol on hot parts.
Step 2: Thoroughly clean the fuel tank – remove invisible dirt
Draining old fuel isn’t enough. The bottom of the tank often has a layer of sticky gum, rust, or debris. If you don’t clean it out, fresh fuel will be contaminated immediately.
Cleaning steps:
- Remove the tank (for a deep clean): On most walk‑behind mowers, the tank is mounted above the engine. Unbolt it with a screwdriver or socket wrench, and disconnect the fuel line. Take a picture or note where each hose goes.
- Pour out any remaining fuel, then put a small amount of fresh petrol (about 100 ml) into the tank along with a few clean nuts or small stones.
- Tighten the fuel cap and shake the tank vigorously for several minutes. The nuts will bounce around inside, knocking off gum and rust stuck to the walls.
- Pour out the cleaning fluid and wipe the inside of the tank with a clean cloth or paper towel. You can also blow it dry with compressed air.
- If the tank is heavily rusted inside, replace it with a new one – rust flakes that get into the carburettor will cost more to fix than a new tank.
For users who can’t easily remove the tank, a “fuel system cleaner” added to old fuel and run for a few minutes before draining can help, but it’s not as thorough as a physical cleaning.
Step 3: Set up a fuel management system – one routine covers half a year
Once the tank is clean, the key is preventing the same problems from coming back. Here’s a simple, practical “three‑step fuel management” routine for farmers and dealers:
- Use a fuel stabiliser
If you have to use ethanol‑blended fuel in your area, or if the mower will sit unused for more than a month, strongly recommend adding fuel stabiliser at every fill‑up. It prevents oxidation and moisture absorption, keeping petrol fresh for 6‑12 months. A small bottle of stabiliser costs little – but it saves expensive carburettor repairs.
How to use: Before filling the tank, pour in the recommended amount of stabiliser (check the label – typically 1 ml per litre of petrol), then fill with fresh petrol. Run the mower for a few minutes so the stabiliser reaches the carburettor.
- Install or replace the fuel filter
Many mowers come with a fuel filter from the factory, but owners often forget to change it. Replace the fuel filter every 200 working hours or once a year. If the mowers you sell don’t have a filter, you can recommend customers add a universal in‑line filter (costs very little) – it stops dirt and rust from reaching the carburettor.
- “Dry out” the system before long‑term storage
If the mower will be stored for more than three months (e.g. over winter), the best practice is not to leave the tank full. Instead:
- Drain the fuel tank.
- Start the engine and let it run until it dies from lack of fuel. This burns the remaining fuel in the carburettor float bowl, preventing gum deposits.
- Remove the spark plug, put a few drops of engine oil into the cylinder, pull the starter cord a few times, then reinstall the spark plug. That protects the cylinder (an added bonus).
If draining completely is too much trouble, at least do this: fill the tank with fresh petrol treated with stabiliser, close the fuel cap tightly, and store the mower in a cool, dry place.
Extra tip: What about ethanol‑blended fuel?
Different regions have different petrol grades and ethanol content. E10 (10% ethanol) is usually acceptable, but E15 or higher is not recommended for small engines. Ethanol can corrode old rubber fuel lines and gaskets. If your equipment is older, try to find ethanol‑free petrol (often labelled “Rec 90” or “ethanol‑free”). As a dealer, you can clearly tell customers: damage caused by using petrol with higher than recommended ethanol content is not covered under warranty – this isn’t avoiding responsibility, it’s basic engineering.
Why should you teach your customers this?
As a mower exporter, when you teach your customers to clean the fuel tank and manage their fuel, they’ll have fewer “won’t start” frustrations – and more trust in your brand. Many farmers instinctively think “this mower is poor quality,” when in reality 80% of starting problems are fuel‑related. If you provide a short instructional video or a simple maintenance card, your customers will see you as professional and responsible. Next time they need a new machine or parts, you’ll be the first they call.
To sum up: clean the tank + use fuel stabiliser + replace the filter regularly + dry out the system before long storage. These four actions take less than half an hour, but they can keep a petrol mower running for years longer. A sharp blade gives a beautiful lawn – clean fuel gives a quick, reliable start. You need both.
(If you have any questions about mower maintenance or bulk purchasing, feel free to contact our export team. We not only supply high‑quality petrol mowers – we want to be the knowledgeable partner behind your business.)
