I have never turned my vehicle off while pumping gas in my life and have yet to have an issue. Especially coming from a Northern state where it gets pretty cold you see a lot of people doing the same thing. What is the potential risk or is it all just a myth?
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Because you can start a fire.
How could you start a fire? When you grab the pump and start filling up the tank, gas vapors are emitted. Running cars can produce a lot of heat and electricity which can ignite the fumes and cause a massive fire.
Running your engine while pumping gas increases the risk of fire because your engine produces not only heat, but also static electricity while running. Objectively the risk is quite low, but it’s definitely much safer to turn the engine off.
I think I has to do with general safety these days. You don’t want the average person jumping in and out of a running car. It’s just too easy to forget to engage park, and suddenly you’re car is driving away from the pump… While attached to the hose.
It’s bad for the Emissions system. When you open the gas cap while the car is running you can cause the ECM to think there is a leak in the Vacuum System. Don’t be lazy.
Just turn it off.
For one, having the engine running while the gas cap is off messes with the pressure in the engine. So even putting aside any safety stuff, it’s not great.
For something far more important, you are deliberately firing sparks in the vicinity of open gasoline. I don’t really understand how you *don’t* see the risk inherent in that.
But just like a lot of stupid and dangerous things, it only goes wrong when some other thing goes wrong, like for example, holding the spray handle down when you take it out of the tank, where it hits a hot running engine, and the vapors catch fire.
You have a much increased risk of a static discharge, through the alternator, where you can get ignition from.
It’s not commonplace, but long time ago, when I was a trainee for a particular UK Oil company I got to watch what happened in that case. It took 11 seconds before the steel beams started to melt. The person pumping didn’t survive.
Same reason you turn your phone off there, and never ever smoke. You might be lucky, but you really don’t want to be the example of what not to do in those cases, you usually won’t get a second chance.
I live in Canada where the temperature goes down to -50 in the winters. I have never ever seen someone pumping gas with their car running. This is incredibly dangerous due to fuel vapors and the constant spark of a running engine.
Even the static electricity of opening and closing your door can start a fire with the gas vapors emitted from pumping.
I work in a company that has a chain of gas stations and get copied on emails when fires occur at the pumps. It happens more than you think.
Bottom line… low risk, but there is a risk.
ELI5: it’s an excess of caution, because giant explosions are bad. Also, you’ll confuse the car and cost yourself money. Plus, if you do it you’ll scare the people around you, which is rude.
I suspect it hasn’t been a genuine safety issue in decades.
The sparks and heat and so forth from the engine that could cause a fire are pretty well contained. Google tells me the auto-ignition temperature of gasoline vapors is over 546°F. If you have sparks or heat like that outside the engine compartment, you have a giant safety problem before you get to the gas station. If you have heat that high (except at the exhaust manifold) or free sparks in your engine compartment, get to your mechanic,.
You know there are idiots out there who violate every safety rule. How often do you hear about gas stations exploding? If Shell or Exxon thought you could blow up their station, kill their customers, and tie them up in lawsuits for years they would not let you pump your own gas.
On the other hand, the car’s computer is looking for gas leaks (for emissions reasons) and it expects the gas tank to be pressurized. You open the gas cap when the engine is running the computer will think gas fumes are leaking into the environment and it will throw the check engine light on. You can get that read at the auto-shop for free, or so I’ve heard, but if you go to a mechanic they’re going to charge you $50-100 to check everything over and turn it off.
But ask yourself, if you were filling up and saw the person one pump over was filling with their engine running, would you drop everything and run for your life? No? Then you don’t truly believe there’s a risk. Because you haven’t heard of anyone being caught in an explosion at a gas station. It’s pretty rare. The companies that run those stations are not stupid. They are very, very much not stupid.
This is my opinion, and nothing in my background suggests it should be read as authoritative.
It’s just common sense you know. “I have yet to have an issue” are like famous last words because if you do get an issue, it’s gonna be the big one, let alone possibly the last one.
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