Project Fix

Lawn mower

Petrol mower will not start

Fuel, air, spark — check them in that order and most mowers come back to life.

DifficultyModerate
Time it takes45 minutes
What you needSpark plug spanner, Fresh fuel, New air filter

Before you start

Petrol is highly flammable and the blade can turn while you work. Lead off, engine cool, outdoors only.

  1. 1

    Make it safe

    Pull the spark plug lead off before going anywhere near the blade, and work outdoors.

  2. 2

    Replace old fuel

    Drain fuel that has sat for months and refill with fresh. Stale petrol is the single most common cause.

  3. 3

    Check the air filter

    Take the filter out. If it is grey and clogged, clean or replace it.

  4. 4

    Check the spark plug

    Remove the plug. A black, oily or wet tip means it needs cleaning or replacing.

  5. 5

    Prime and pull

    Refit everything, press the primer bulb the number of times in the manual, and start it on a hard flat surface.

  6. 6

    Clear the deck

    Tip it with the fuel cap side up and scrape out packed grass so the engine is not fighting the blade.

When to stop and get help

If it still will not fire with fresh fuel, clean filter and a new plug, the carburettor likely needs stripping — worth a small-engine shop.

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