Explosive fumes can remain despite cleaning and flushing the fuel system, meaning there is a risk of ignition when carrying out repairs to the fuel tank or filler neck, so this should always be done by a professional with experience of critical, and potentially dangerous, work on this aspect of the car. The fuel tank must not be placed in an area where sparks or open flame could contact vapours if the tank is removed from the vehicle, e.g., garages that use gas type appliances, where there may be pilot lights or burners that could explode.