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  #1  
Old 03-11-2012, 08:04 PM
copperwindow copperwindow is offline
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turning the car off when you pump gas

do you really need to turn the car off when you pump gas? what can happen if you don't, and what are the chances?
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  #2  
Old 03-11-2012, 08:16 PM
Lacunae Matata Lacunae Matata is online now
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I'm curious about this one. My husband always leaves it running, and it makes me vaguely nervous!
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  #3  
Old 03-11-2012, 08:16 PM
SmartAlecCat SmartAlecCat is offline
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Also: how many things have actually happened to any cars that didn't turn off?

How is it turning your car off on one side of the gas pump different from the car starting and driving away on the other side of the gas pump?
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  #4  
Old 03-11-2012, 08:49 PM
eldowan eldowan is offline
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My WAG:

On a car with a faulty electrical system, there is a slight possibility of a bad ground (or something) that causes a spark when the nozzle is inserted into the tank, causing an explosion.

Not likely, and shot from the hip, but have you seen some of the cars people drive?
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  #5  
Old 03-11-2012, 09:03 PM
automagic automagic is offline
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My best guess is that it has to do with fuel vapors.

Until fairly recently most cars with fuel injection systems had return lines. This means that any fuel that was sent to the engine by the fuel pump, but not used by the engine, was sent back to the fuel tank. The returning fuel was at a considerably higher temperature than the fuel in the the tank. The higher temperature is normally not a problem since the fuel tank is sealed but it you open it, like when you pump gas, the vapors can escape. The fuel vapors can harm the atmosphere and also increase the chance of fire.
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  #6  
Old 03-11-2012, 09:05 PM
beowulff beowulff is offline
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Click and Clack have discussed this at length. Their conclusion: it reduces the possibility (no matter how remote) of accidents, both fire, and collision (putting the car into gear while reaching for your wallet, etc.)

ETA: newer cars will set the Check Engine Light if they detect the gas cap is loose while running, so that's another reason not to do this.

Last edited by beowulff; 03-11-2012 at 09:06 PM..
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  #7  
Old 03-11-2012, 09:24 PM
Zsofia Zsofia is offline
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A month ago I had to sit and wait at a pump while a truck moved back a tad so I could get the hose to reach, so I ended up accidentally leaving the car on (which I only realized after I fueled up!) I scooted out of there in terror that somebody noticed - I'm so glad to realize that the risk of me blowing everybody up was relatively small.
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  #8  
Old 03-11-2012, 09:26 PM
beowulff beowulff is offline
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Quote:
Originally Posted by eldowan View Post
My WAG:

On a car with a faulty electrical system, there is a slight possibility of a bad ground (or something) that causes a spark when the nozzle is inserted into the tank, causing an explosion.
Impossible.
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  #9  
Old 03-11-2012, 09:30 PM
aceplace57 aceplace57 is offline
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Cars have been known to jump out of park and run into their owners. I cite one example, but this has come up with cars consistently since I grew up in the 70's.

I never step out of my car without turning it off. Certainly, I turn it off before filling up. I really hate seeing any kids standing near cars idling in park. Its just foolish and an unnecessary risk.

Quote:
On June 10, 1980, NHTSA made an initial determination of defect in Ford vehicles with C-3, C-4, C-6, FMX, and JATCO automatic transmissions. The alleged problem with the transmissions is that a safety defect permits them to slip accidentally from park to reverse. As of the date of determination, NHTSA had received 23,000 complaints about Ford transmissions, including reports of 6,000 accidents, 1,710 injuries, and 98 fatalities--primarily the young and old, unable to save themselves--directly attributable to transmission slippage.
http://www.autosafety.org/ford-trans...lure-hold-park

Last edited by aceplace57; 03-11-2012 at 09:33 PM..
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  #10  
Old 03-11-2012, 09:32 PM
engineer_comp_geek engineer_comp_geek is offline
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Cars generate an electrical charge while running, due mostly to the rubber belt(s) moving around the front of the engine (they also generate static charge just due to moving down the road). If you leave the car running it makes it more likely for you to have a static discharge when you reach for the pump when you are done fueling, which can lead to a pump fire if the mixture of fuel and air is just right.

On average there are roughly a half a dozen or so pump fires due to static electricity every year. Not all of those are due to leaving the engine running. Many for example are caused by people (more often women) getting back into the car to keep warm and generating a static charge when they slide across the seat to get back out. Considering how many people fuel up every day the chances of something bad happening are admittedly pretty small. But, they aren't zero. Turning off the engine greatly reduces those chances, and if you do go back inside the car to keep warm, when you get back out, touch something metal on the car some distance away from the fuel pump and your gas tank to get rid of any charge that may have built up.

If you are interested in the details, the petroleum equipment institute (PEI) keeps statistics about these incidents, which used to be available on their web page. I haven't checked lately but they are probably still there. You don't get a great deal of detail about every event, but sometimes they note things like whether or not the vehicle was left running.

Last edited by engineer_comp_geek; 03-11-2012 at 09:34 PM..
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  #11  
Old 03-11-2012, 09:49 PM
eldowan eldowan is offline
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Originally Posted by beowulff View Post
Impossible.
Good to know, ignorance fought.
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  #12  
Old 03-11-2012, 09:50 PM
Rick Rick is offline
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Quote:
Originally Posted by beowulff View Post
Impossible.
Would you like to bet on that?
Not caused by a loose ground, but static discharge none the less.
Also fires can occur if you fill a gas can while in the bed of a pickup that has a bed liner.
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  #13  
Old 03-11-2012, 09:55 PM
Ms Boods Ms Boods is offline
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According to Jay Leno, if you drive a 1955 Buick Roadmaster, if you leave the car on, you might get ahead of the pump.

http://www.youtube.com/watch?v=dlXJrcSBIH0
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  #14  
Old 03-11-2012, 10:45 PM
Digital is the new Analog Digital is the new Analog is offline
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I had a friend who insisted that if it were really dangerous, there would be an interlock that forces us to turn the car off. *sigh*

I don't know the technical answer..but I feel certain if I turn the car off, I won't be in danger. If I leave the car on, I may or may not be in danger. Given those two choices, it's easy..

-D/a
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  #15  
Old 03-11-2012, 11:09 PM
beowulff beowulff is offline
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Quote:
Originally Posted by Rick View Post
Would you like to bet on that?
Not caused by a loose ground, but static discharge none the less.
Also fires can occur if you fill a gas can while in the bed of a pickup that has a bed liner.
He said "electrical problem with the car" - static discharge can occur whether the car is running or not.
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  #16  
Old 03-11-2012, 11:14 PM
Elendil's Heir Elendil's Heir is offline
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Quote:
Originally Posted by Ms Boods View Post
According to Jay Leno, if you drive a 1955 Buick Roadmaster, if you leave the car on, you might get ahead of the pump.

http://www.youtube.com/watch?v=dlXJrcSBIH0
Peter Arno had a cartoon like that 'way back when in The New Yorker, which I can't find online. A gas station attendant is filling up an enormous, idling convertible and says to the driver, "Would you mind turning it off, sir? It's gaining on me."
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  #17  
Old 03-12-2012, 12:14 AM
AaronX AaronX is online now
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I've only seen someone do it once (I was in the car) and it made me very nervous, but I'm glad to know other people do it too.
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  #18  
Old 03-12-2012, 01:42 AM
Dog80 Dog80 is offline
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My car (Peugeot 207) has a locking cap that opens with the car key. So you have to turn the car off to release the key and then go out and unlock the cap.

Once the cap is opened, the key gets stuck there so you can't use it until you put the cap back in place and lock it again. However, there is a small button on the side of the cap that if depressed releases the key.

I once did that and restarted the car while it was refueling. One little problem though. Althought the car was filled to the brim, the needle got stuck somewhere in the middle. I did a long ride after that, but the needle didn't get where it was supposed to be. Eventually the problem fixed itself the next time I refuelled the car.
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  #19  
Old 03-12-2012, 05:32 AM
pullin pullin is online now
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Quote:
Originally Posted by Rick View Post
Would you like to bet on that?
Not caused by a loose ground, but static discharge none the less.
Also fires can occur if you fill a gas can while in the bed of a pickup that has a bed liner.
Is it the bedliner that isolates the gas can? I've never really understood this one. I figured that the metal-to-metal contact when you insert the nozzle in your car's fuel tank zeroes out any building charge, and that what is missing when filling a fuel tank in an ungrounded car.

I once got a lecture about this from a well-meaning individual while filling a bunch of gas cans in my pickup bed (I didn't want to lift them all back in). I silenced him by pointing out that I had grounded the bed itself with a large piece of angle-iron running to the asphalt. I have no idea whether that would work, or whether I need to ground to the pump, like they do with airplanes.

Last edited by pullin; 03-12-2012 at 05:34 AM..
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  #20  
Old 03-12-2012, 06:35 AM
Rick Rick is offline
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The problem occurs when you have a plastic gas can. Static builds up from the fuel flowing into the can. If the can is on the ground the charge disapates. However if you leave the can in the bed that has a bed liner the can is insulated. When you remove the nozzle A spark can jump and ignite the vapors.
I saw this happen at Willow Springs Raceway once. Guy filled up a 5 gallon race jug sitting in the bed of his truck. The fire was IMPRESSIVE. They red flagged the race and rolled all the fire equipment to deal with it.
Bottom line is put the can on the ground when you fill it.
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  #21  
Old 03-12-2012, 06:57 AM
Machine Elf Machine Elf is offline
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Quote:
Originally Posted by Rick View Post
The problem occurs when you have a plastic gas can. Static builds up from the fuel flowing into the can. If the can is on the ground the charge disapates. However if you leave the can in the bed that has a bed liner the can is insulated. When you remove the nozzle A spark can jump and ignite the vapors.
I saw this happen at Willow Springs Raceway once.
Seems like this sort of thing pops up on the local news once a year or so: gas station surveillance cameras catch somebody filling up a gas can on the bed of a pickup truck, and suddenly there's a fire. In the best outcome, just the truck burns; in the worst outcome, the victim flings the hose and/or tips the gas can and gets fuel on himself, resulting in serious burns.
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  #22  
Old 03-12-2012, 07:26 AM
CookingWithGas CookingWithGas is offline
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Quote:
Originally Posted by beowulff View Post
He said "electrical problem with the car" - static discharge can occur whether the car is running or not.
Fires from sparks caused by static buildup have been mistakenly interpreted as fires caused by cell phones.
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  #23  
Old 03-12-2012, 08:51 AM
Corcaigh Corcaigh is offline
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Originally Posted by Dog80 View Post
My car (Peugeot 207) has a locking cap that opens with the car key. So you have to turn the car off to release the key and then go out and unlock the cap.

Once the cap is opened, the key gets stuck there so you can't use it until you put the cap back in place and lock it again.
I had the same make (different model) car for over a decade, it's just become a habit to me to turn the engine off when I fill 'er up. Previously to that my father had a large saloon that had a lockable flap over the petrol cap, so I grew up with people switching off the engine when they filled up.

I was told it was to do with preventing a fire, caused by a spark igniting the fumes - if the engine is running it supposedly causes a bigger fire/explosion.

I've only ever met one person who leaves the engine running when they fill up
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  #24  
Old 03-12-2012, 08:57 AM
anson2995 anson2995 is offline
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We've discussed this here several times, and the consensus has been that there's no evidence that a running engine creates a risk of igniting fuel vapors and exploding. If it did, it would be just as dangerous to pull into the service station as it is to sit idling.

I asked back then for any cites of instances where this actually happened, and neither I or other Dopers could find a single example.

The risk of the car jumping into gear is almost entirely an issue of operator error, and nearly impossible with an automatic transmission. aceplace57 points to an industry report from 1980. it's worth pointing out that this was more than 30 years ago, and very few of those cars are still on the road. The number of cars and light trucks with manual transmission has dropped from about 40% to 5% since then.
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  #25  
Old 03-12-2012, 09:01 AM
tullsterx tullsterx is offline
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What is the rational for leaving it running? I can't think of any good reason.
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  #26  
Old 03-12-2012, 10:10 AM
Gedd Gedd is offline
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Originally Posted by tullsterx View Post
What is the rational for leaving it running? I can't think of any good reason.
Heat? Sitting in the car while it's filling up (which I believe is a major factor in fires at the pump). Making a quick getaway? Umm . . . wasting gas?
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  #27  
Old 03-12-2012, 10:30 AM
Leaffan Leaffan is offline
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How do you sit in the car while the pump is running? Don't all the pumps have that latching mechanism defeated, to prevent you from leaving a running pump? They do here.
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  #28  
Old 03-12-2012, 10:34 AM
Fubaya Fubaya is offline
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Young kids fall asleep in the car pretty easily. When i pull into a gas station and my daughter is asleep and it's 90 degrees outside, I leave it running
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  #29  
Old 03-12-2012, 10:44 AM
gazpacho gazpacho is offline
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Originally Posted by Leaffan View Post
How do you sit in the car while the pump is running? Don't all the pumps have that latching mechanism defeated, to prevent you from leaving a running pump? They do here.
Where is here? In California most of the pumps have a little catch you can flip down so you don't have to hold the pump while it is filling. I seem to recall the same thing being true in Utah, Colorado, Arizona and New Mexico.
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Old 03-12-2012, 10:46 AM
beowulff beowulff is offline
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Originally Posted by anson2995 View Post
We've discussed this here several times, and the consensus has been that there's no evidence that a running engine creates a risk of igniting fuel vapors and exploding. If it did, it would be just as dangerous to pull into the service station as it is to sit idling.

I asked back then for any cites of instances where this actually happened, and neither I or other Dopers could find a single example.

The risk of the car jumping into gear is almost entirely an issue of operator error, and nearly impossible with an automatic transmission. aceplace57 points to an industry report from 1980. it's worth pointing out that this was more than 30 years ago, and very few of those cars are still on the road. The number of cars and light trucks with manual transmission has dropped from about 40% to 5% since then.
I had to rescue my next-door neighbor when she got out of her car before turning it off (or putting it in park). The car lurched forward, and she got caught in the seatbelt and dragged. She was extremely lucky that she didn't get her legs crushed. So, I can see that if someone gets out of the habit of turning the car off, then they increase their chances of leaving the car in gear and running when they pull up to the gas pump, with the predictable consequences.
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  #31  
Old 03-12-2012, 10:47 AM
Duckster Duckster is offline
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Long ago in a galaxy far, far away, the chances of a "runner" were much more than today. Back then it was possible to fuel your vehicle and then take off without paying.

I knew one self-serve station manager that always kept a quart of oil (paper can) on top of one of the pumps. I asked him why it was there, and doesn't he risk getting it stolen. Yes, there was always a risk someone would steal it, but the cost of a quart of oil was less than the cost of a runner with a tank of gas. Seems the station manager had a pretty good throwing arm so if he had a runner, he would lob that quart of oil at the fleeing vehicle. It made it easier for the police to track down the vehicle.

During the winter, the can of oil was a bit "harder" than summer. More often than not the can would go through the rear window before breaking up.

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  #32  
Old 03-12-2012, 11:08 AM
Leaffan Leaffan is offline
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Originally Posted by gazpacho View Post
Where is here? In California most of the pumps have a little catch you can flip down so you don't have to hold the pump while it is filling. I seem to recall the same thing being true in Utah, Colorado, Arizona and New Mexico.
Here is Ontario, Canada. The catches are all removed so that you can't walk away from a running pump. (You could perhaps stick the gas cap or something in there I suppose.)
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Old 03-12-2012, 11:30 AM
Kimballkid Kimballkid is offline
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Originally Posted by Leaffan View Post
(You could perhaps stick the gas cap or something in there I suppose.)
And a lot of idiots do.
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  #34  
Old 03-12-2012, 11:34 AM
Rick Rick is offline
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Originally Posted by tullsterx View Post
What is the rational for leaving it running? I can't think of any good reason.
car full of people in 100+ weather.
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Old 03-12-2012, 11:53 AM
Really Not All That Bright Really Not All That Bright is offline
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Originally Posted by Leaffan View Post
How do you sit in the car while the pump is running? Don't all the pumps have that latching mechanism defeated, to prevent you from leaving a running pump? They do here.
Not in the US- some gas station operators remove them (or they break), most don't. The pumps here all have automatic shutoffs, though; I assume they do in Canada too.
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  #36  
Old 03-12-2012, 12:03 PM
Leaffan Leaffan is offline
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Originally Posted by Really Not All That Bright View Post
Not in the US- some gas station operators remove them (or they break), most don't. The pumps here all have automatic shutoffs, though; I assume they do in Canada too.
Yep.
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Old 03-12-2012, 12:09 PM
engineer_comp_geek engineer_comp_geek is offline
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Quote:
Originally Posted by pullin View Post
Is it the bedliner that isolates the gas can? I've never really understood this one. I figured that the metal-to-metal contact when you insert the nozzle in your car's fuel tank zeroes out any building charge, and that what is missing when filling a fuel tank in an ungrounded car.

I once got a lecture about this from a well-meaning individual while filling a bunch of gas cans in my pickup bed (I didn't want to lift them all back in). I silenced him by pointing out that I had grounded the bed itself with a large piece of angle-iron running to the asphalt. I have no idea whether that would work, or whether I need to ground to the pump, like they do with airplanes.
The bedliner does isolate the gas can, so the cans can have a charge differential with respect to the rest of the truck or with the pump, allowing a spark to occur. You could still have a charge differential with respect to yourself/the pump/the truck/gas cans even if you have metal cans sitting in contact with a metal bed. The semi-enclosed bed of a truck also tends to catch fumes that would otherwise blow away in the wind, increasing the risk.

The angle-iron on would ground any charge on the truck. A direct connect to the pump would make a better ground. In either case, you still have the issue where the charge may be built up on you and not on the vehicle (typical of a person sliding across the seat in the winter, for example). I suppose you could be absolutely anal about it and attach a ground strap to your wrist and the pump as well. A more practical solution is just to touch something metal on the truck somewhere away from where the fuel vapors might be to equalize the charge between the truck and yourself.

Quote:
Originally Posted by anson2995 View Post
We've discussed this here several times, and the consensus has been that there's no evidence that a running engine creates a risk of igniting fuel vapors and exploding. If it did, it would be just as dangerous to pull into the service station as it is to sit idling.
Keeping the engine running keeps charge building up, mostly due to the moving belts. Otherwise, any charge built up would dissipate through the vehicle's tires. So there is a slightly higher risk with leaving the engine running.

In order to have a fire, you need fuel, oxygen, and a source of ignition. When you pull into the gas station, you generally don't have fuel vapors just hanging about, so there's no fuel source. If you don't keep the engine running, any charge built up on the vehicle from the engine or just from the vehicle moving through the air will dissipate quickly, removing your potential source for ignition. So in that respect it is more dangerous to leave the vehicle running than it is just to pull into the station.

Quote:
Originally Posted by anson2995 View Post
I asked back then for any cites of instances where this actually happened, and neither I or other Dopers could find a single example.
There are two examples in the PEI report (I just checked - you can get to it from Rick's link upthread) where they note that the vehicle had been left running. It's not clear from the circumstances though if the running engine actually had anything to do with the static discharge. In both cases the driver got in and out of the car as well, which may have generated the static charge.
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  #38  
Old 03-12-2012, 12:22 PM
MLS MLS is offline
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I always turn off the engine, not just because the sign on the pump says so, but because I see no reason to waste gas. Even if it's 100 degrees, 5 minutes of no AC isn't going to kill anyone. Why, back in MY day, nobody had an air-conditioned car. <shakes fist> Dam kids these days and their fancy air-conditioned cars.....
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  #39  
Old 03-12-2012, 01:05 PM
JoshuaSD JoshuaSD is offline
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My two cents:

It takes only a few minutes to fill the tank on a car. (Maybe 10 minutes for a big truck?) When our statement is that we have kids in the car so we are leaving it running to protect them from the heat/cold I cant buy that. The car does not heat up that fast even in the hot summer sun.

Google "child knocks car into drive" and the results should convince anyone that this is a very bad idea. Add to the problem of the car careening through the gas station window that the pump being torn out may have sprayed you with flammable fuel and rescue is now even more hampered. One spark from a car half way through a store window is not that unlikely.

Again just an opinion.
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  #40  
Old 03-12-2012, 01:17 PM
Machine Elf Machine Elf is offline
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Originally Posted by Really Not All That Bright View Post
Not in the US- some gas station operators remove them (or they break), most don't. The pumps here all have automatic shutoffs, though; I assume they do in Canada too.
The automatic shutoffs are not 100% reliable. A couple of weeks ago I was pumping gas and left the nozzle unattended while I cleaned the rear window of my car. I started hearing splashing noises and immediately realized my tank was full and the dispenser was still pumping gas; I ended up with maybe a quart of gas on the ground before I got it stopped.

Getting gas? Shut your car off, and don't get too far from the nozzle. Definitely don't get back into your car; not only can this generate static electricity, but you may not be able to respond in a timely manner if the automatic shutoff doesn't work. Your cell phone won't start a fire, but you probably should give your full attention to what you're doing while you refuel your vehicle; make/take the call after you're done.
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  #41  
Old 03-12-2012, 02:05 PM
anson2995 anson2995 is offline
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Originally Posted by engineer_comp_geek View Post
There are two examples in the PEI report (I just checked - you can get to it from Rick's link upthread) where they note that the vehicle had been left running. It's not clear from the circumstances though if the running engine actually had anything to do with the static discharge. In both cases the driver got in and out of the car as well, which may have generated the static charge.
Not disputing the issue of static charge, just the idea that the engine itself createsan explosion risk.

FWIW, I linked to an earlier version of the PEI report in the 2005 thread I referenced, so I'm with you on this one.
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  #42  
Old 03-12-2012, 02:22 PM
Morgenstern Morgenstern is offline
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There are a few things those of you who fuel your car with the engine running may have overlooked.

In some jurisdictions, it's illegal to fuel a running vehicle. That probably explains why the stations pay for those "Turn vehicle off when fueling" sighs posted.

Also, modern vehicles, with sophisticated emission systems, frequently run system tests while the vehicle is running. It has no way of knowing if your're stopped at a traffic light or for fuel. It's just a matter of time before such a test happens while you're fueling your car with the engine running. You'll first notice a problem when you see the "Check Engine" light illuminated on your instrument cluster. This is because the fuel system is a sealed unit. The vapors are captured and later burned.
Opening the fuel tank with the engine running will trigger an error code IF a system test runs at that time.

After a trip to the mechanic, and a wallet a hundred dollars lighter, you'll understand the the advantage of turning off your vehicle when fueling.
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  #43  
Old 03-12-2012, 02:23 PM
Machine Elf Machine Elf is offline
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Originally Posted by anson2995 View Post
Not disputing the issue of static charge, just the idea that the engine itself createsan explosion risk.
Failure Analysis: Cell Phone Usage at Gas Stations

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Originally Posted by Failure Analysis
Motor Vehicles as Ignition Sources
The engine in a motor vehicle can act as an ignition source if operated in a combustible environment. Some potential ignition sources are: alternator brushes, starter motor assembly, electric fans on the radiator, grounded spark plug wires, and even hot surfaces on an exhaust system of an abnormally performing engine. Most of these sources would be closer to the ground than a cell phone in operation, and thus closer to any combustible mixtures of gasoline vapor and air resulting from filling operations or a spill.
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Old 03-12-2012, 02:54 PM
naita naita is offline
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Originally Posted by engineer_comp_geek View Post
Keeping the engine running keeps charge building up, mostly due to the moving belts. Otherwise, any charge built up would dissipate through the vehicle's tires. So there is a slightly higher risk with leaving the engine running.
Wouldn't that require the pulleys to be fixed to bits of car that were electrically separate? And where's the charge supposed to come from that dissipates through the tires?
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Old 03-12-2012, 03:11 PM
engineer_comp_geek engineer_comp_geek is offline
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Originally Posted by naita View Post
Wouldn't that require the pulleys to be fixed to bits of car that were electrically separate?
It may not exactly be an ideal Van de Graaff generator but the moving belts can still generate a charge. I found this video which you may find interesting:
http://www.youtube.com/watch?v=6d7pfA_bo6s

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Originally Posted by naita View Post
And where's the charge supposed to come from that dissipates through the tires?
Engine belts and pulleys aside, cars will also generate a charge just from moving down the road. It's pretty much the same process as by which clouds become electrically charged.
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Old 03-12-2012, 03:19 PM
kanicbird kanicbird is offline
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Originally Posted by beowulff View Post

ETA: newer cars will set the Check Engine Light if they detect the gas cap is loose while running, so that's another reason not to do this.
Having refilled a couple of times without shutting down the engine over the years, and several times at full service stations leaving the engine running I can attest that this short time of taking the fuel cap off does not set off the check engine light.
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Old 03-12-2012, 03:44 PM
Tastes of Chocolate Tastes of Chocolate is offline
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Originally Posted by kanicbird View Post
Having refilled a couple of times without shutting down the engine over the years, and several times at full service stations leaving the engine running I can attest that this short time of taking the fuel cap off does not set off the check engine light.
Having accidentally not tightened the gas cap all the way, and having the check engine light come on very shortly after restarting the engine, I can attest that you are taking your chances.
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Old 03-12-2012, 03:55 PM
Machine Elf Machine Elf is offline
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Originally Posted by Tastes of Chocolate View Post
Having accidentally not tightened the gas cap all the way, and having the check engine light come on very shortly after restarting the engine, I can attest that you are taking your chances.
Once the offending condition (unsealed fuel tank) is fixed, these kinds of fault codes reset themselves after a few key/start cycles; it's not typically necessary to interface with the ECU and force a reset.
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Old 03-12-2012, 04:02 PM
anson2995 anson2995 is offline
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Originally Posted by Machine Elf View Post
Failure Analysis: Cell Phone Usage at Gas Stations
Quote:
Originally Posted by Failure Analysis
The engine in a motor vehicle can act as an ignition source if operated in a combustible environment. Some potential ignition sources are: alternator brushes, starter motor assembly, electric fans on the radiator, grounded spark plug wires, and even hot surfaces on an exhaust system of an abnormally performing engine. Most of these sources would be closer to the ground than a cell phone in operation, and thus closer to any combustible mixtures of gasoline vapor and air resulting from filling operations or a spill.
And if any of those things are an ignition source while you're pumping gas, they're also an ignition source as you're pulling in or as you're exiting.

As with the idea of cars slipping into gear, this is an example of an already dangerous car continuing to be dangerous. The real question here is whether a new risk is created by leaving an otherwise un-dangerous car running while you are filling up. And while the static issue is real (and well documented), it is not directly related to leaving the engine running.

Its important to understand what are real dangers and what aren't. For example, its virtually impossible for a cell phone to accidentally trigger an explosion, but it's very possible for a cell phone to distract you and cause an overflow... which could be dangerous.
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  #50  
Old 03-12-2012, 04:05 PM
naita naita is offline
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Originally Posted by engineer_comp_geek View Post
It may not exactly be an ideal Van de Graaff generator but the moving belts can still generate a charge. I found this video which you may find interesting:
http://www.youtube.com/watch?v=6d7pfA_bo6s

Engine belts and pulleys aside, cars will also generate a charge just from moving down the road. It's pretty much the same process as by which clouds become electrically charged.
That makes sense. I wouldn't have thought the pulleys were sufficiently isolated from the rest of the engine for that to occur and your mention of both pulleys and belts, and charge dissipating through the tires in the same set of arguments had me confused.
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