There are signs at petrol stations advising motorists to turn their engine off before refuelling their car.
Naturally, this strikes me as such an obvious thing to do that it stands to reason a sign is necessary, but it did get me thinking: What would happen if someone didn’t turn their engine off whilst refuelling their car?
I’m not talking about specialist racing cars being refuelled in the pit or anything like that; just normal everyday cars at a normal, everyday petrol station.
Anyone?
Isn’t the concern more with a spark igniting fuel fumes than with the possibility of a mechanical threat to the engine?
Nothing probably. I’ve done it twice in my life - both when I had a dead and recently re-charged battery and couldn’t turn it off or else it probably wouldn’t start again. Nevertheless a bad idea, because of the spark/fumes possibility, I’ve always believed.
Leaving the engine running is not all that dangerous. And its not so different to a race car.
Its not to protect the engine or anything else, its simple because of the worry about sparks andd petrol fumes - the same reason why you shouldn’t talk on your cell phone or smoke or have your cell phone on your belt while refuelling.
I figured it might be something to do with sparks and petrol fumes… it’s certainly not something that strikes me as A Good Idea, but it’s not something I can see causing a smallish mushroom cloud to rise over a suburban petrol station, either.
When I worked in Antarctica, we always left the engine running while refuelling. As far as I know, there have been no mushroom clouds from doing this.
In the USA, it has potential to damage part of the pollution control devices in some autos.
It is likely the ‘check engine’ light will come on, too. It will go off after a few drives.
Most of the time, nothing will happen.
On very rare occasions, you’ll ignite fuel vapors and end up having a very bad day.
A running car generates static electricity, due mostly to the moving belt on the engine. If you shut the car off, this charge generally dissipates fairly quickly. If you leave the engine running, you keep building up the charge, putting you at a greater risk.
Just to get an idea of the magnitude of the risk, there are on average roughly half a dozen pump fires caused by static discharge in the U.S. per year. Considering how many millions of folks fill up their cars every day, half a dozen is a pretty small number, and it also includes ALL static discharge fires. A running engine is not the most likely type of static discharge to cause a pump fire. The most likely cause of this sort of pump fire is someone (more often than not female) getting back into the car, sliding across the seat, and getting out and touching the pump handle. It’s been a while since I’ve seen the statistics, but I think there’s been about four or five cases of a running engine causing a fire in the past decade or so. So it’s not real likely.
But it’s not impossible either.
I don’t recall anyone dying from this sort of pump fire, but there have been many vehicles and pumps destroyed, and IIRC one dog has been killed.
By the way, since bengangmo mentioned cell phones, it should be noted that there has never, ever, been a pump fire caused by a cell phone. Not one.
That’s my understanding too. Besides, whilst Mythbusters isn’t the most stellar “I told you so!” source in the universe, given their penchant for explosions, I’m inclined to believe that if Adam & Jamie can’t cause an explosion using a cellphone and petrol (or the fumes theoreof), then it’s not really a possibility.
I had a car once that had such poor mileage, if I left the engine running while refueling I could potentially burn the gas faster than the flow from the pump could replenish it, causing a vacuum lock between the pump and my fuel tank.
Would I lie to you?
Indeed, the cell phone ignition hazard is bullshit. Most thorough report right here.
That said, I do think it’s a good idea to stay off the phone while refueling so as to have both hands (and all of your mind) available to attend to the task at hand.
Cite? While is it possible to trip a CEL on some cars due to taking the gas cap off at just the right time, I have never heard of any damage resulting from this, What device, and what is the damage?
as has been mentioned, sparks and fuel vapors. Back in the days when those regulations were written cars were a much dicier proposition then they are today. Also the fuel tank on some cars was located very near the engine on some cars. The Model A Ford for example had the gas cap just in front of the windshield. Leave that sucker running and the gas fumes would settle all over the engine as they headed for the ground. One little spark…
One very real risk (?) is if you fill up with the engine running, the gas gauge won’t read correctly for about 10 minutes. This is normal due to the buffering of the gauge.
I seem to recall seeing a video, but I may well be mistaken about the cause - i would need to find and take another look…
I did this just last month. I didn’t realize my wife hadn’t turned off the car and it was windy so I couldn’t hear the engine going. Needless to say, nothing bad happened and no lights went off. I think it’s just one of those excess of caution things. Plus, why would you ever need to leave the engine running, unless the battery is dead?
I’ve left the car running while fueling a few times just from sheer flakiness – from what I can tell, it’s this close to totally harmless.
Isn’t the danger of igniting fumes almost negligible in 2009? When it happens, are there Very Special Factors that made it happen, or is a more random,“can really happen to anyone!” event than I think it is?
For instance, my understanding is that gasoline fumes don’t collect and stay in the same spot in open air. In fact, I’ve heard something to the effect that the super-mildest of breezes (heck, even someone’s breath) could “disintegrate” a house-sized invisi-cloud of gasoline fumes. The upshot being that the fume-ignition issue is a potentially big deal when fueling in an enclosed garage, but pretty much not an issue for modern open-air filling stations. Or so “they” say 
When it’s -15F out, and your wife is sitting in the passenger seat while you pump gas, it’s nice to leave the heat running.
While I agree that the danger is negligible, it is >0. Have you ever been around a gasoline fire?
As far as how easy gas fumes disperse, you must be a heavy breather if you can “disintegrate” a house sized cloud of gas vapor with your breath. I have never heard “them” say that, I would need some kind of cite that shows that “they” are right.
Click and Clack have mentioned that the real danger of fueling with the engine running is not so much sparks igniting the fuel vapors, but rather the fact that it’s very easy to get the car moving if the engine is running. If you leave the car running, and you have a passenger, or a dog in the car, they can easily bump the shift lever and the car will rip the fuel pump hose off. It’s probably less likely today, since most cars have an interlock to prevent the shifter from moving accidentally, but this wasn’t always true.
I do it all the time in the winter. I never considered it a risk. If it was Im sure the gas cap would be engineered to never open when the car is running and pumps would have sensors to not allow gas to pump in that scenario.
So your risk assessment procedure is to simply observe what has officially been identified as risky enough that costly interlocks are required?
I guess texting while driving must not be particularly risky, since it’s not illegal. :smack:
Just so we’re clear: I’m not suggesting that leaving the engine running is particularly risky, only that your method of risk assessment is flawed.