It goes without saying but I'll say it anyway because there are a lot of nob heads out there.
Petrol and petrol vapour is flammable and when it's in a confined space, the petroleum gas can be explosive.
Make sure you are in a well ventilated area, ideally with as little fuel in the tank as possible.
Don't use a naked flame and be careful about anything that can create a spark.
Open the boot and lift the carpet up behind the soft top flap.
