Patricio
It'd be nice, for instance if you are fitting intermediate tyres when it starts raining, why would you have to change the fuelling strategy if you don't want to? It'd be good to have an option to turn off fuelling in a stop
If you want no fuel to be added set the fuel to an amount slightly less than what is still left in the car. You set the target amount of fuel with the UI, not the amount to be added. However fuel can only be added and not removed from a car (except for burning it while driving), so if you set less the car will leave the pit with the same amount it arrives with. You won't shorten pit times doing that though.