Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It only takes a minute to sign up.
Sign up to join this community
Question has been bothering me a while.
When putting fuel at any gas station, when the tank is almost full, the pump just stops and makes a 'THUNK' noise.
I was wondering... how the hell does the pump knows the tank is almost full? There doesnt seem to be a probe that when the fuel touches it it stops the pump, and you can always put a little bit more and be ok...
So how does the pump know how to stop itself?
Simple explanation:
Gas pump handles use air pressure to monitor when to shut off. There is a small tube in the nozzle that when foam or fuel blocks it causes the pressure to change and trips the shutoff.
Detailed explanation (with video):
