All cars must use no more than 105 kg of fuel in the race and must not exceed fuel flow limit of 100 kg/h at any time during an GP event.
Drivers exceeding the fuel flow limit during a race will be immediately excluded from the race results.
From 2010., teams are not allowed to add or remove fuel from a car during a race. In other sessions during a GP weekend they can refuel or drain their cars but only in their garages and only at rate of 0.8 litres per second.
FIA F1 2017. sporting regulations can be downloaded here.