Why is there no refuelling in Formula 1 races?
Why are F1 racing cars no longer refuelled during pitstops in races?
Refuelling during races was prohibited from season 2010 forwards as a part of cutting costs. The teams save some money as they do not need to transport heavy weight refueling equipment around the world. In addition to cost, there is also a safety aspect. The high speed refuelling occasionally ended up in dangerous situations when the driver started driving when the hose was still attached or when fuel spilled on the car or the driver.
A third aspect is environmental issues. Because being environmentally friendly matters more and more to car manufacturers and companies sponsoring F1 racing - the sport wants to be seen as a responsible environmental organisation. So they want to limit the use of fuel F1, which is now limited to a hundred kilograms per race.