Go to your vehicle, Third Eye the vehicle, select Refuel Vehicle, then Insert Nozzle and proceed to fuel.
Once fueling is complete, Third Eye the vehicle again, select Refuel Vehicle, and choose Remove Nozzle.
Third Eye the pump again and return it.
WARNING
Walking away or driving off with the nozzle still in your hand or in the vehicle will cause the pumps to explode.
You will be punished for intentionally blowing up the pumps.