Yesterday was my first time ever filling up my new diesel pusher at the truck lanes at the Pilot in Marianna, FL. It was raining heavily when I arrived. What seemed odd to me was that not a single big rig tractor trailer turned off their engine despite the fact that the pumps indicate that you must turn off your engine.I turned mine off, but was wondering, what exactly are the pros and cons of turning off the engine? Why do so many truckers leave the engine running and should I also leave mine running?And while this post is about diesel engines, I welcome comments about gas engines as well because I've often been curious as to why they have to shut off their engines. I've heard it's a fire risk, but I have some difficulty seeing how. Maybe if someone pours fuel on the engine?

Why wouldn't you turn it off? Too many things could happen, none of them good, if you leave your engine running while refueling. I turn off my car, RV, motorcycle, anything when putting something like combustible fuel into the vehicle! I agree - don't understand why the commercial vehicles don't do so.

I'm not sure why either, except to say before vapor capture systems were developed for both car and gas station hoses the smell of fumes always filled the air. With these improved safety devices the signs remain but I'm not sure the reason does. I do know the safety reasons behind grounding yourself before fueling to avoid static discharge as with the infamous "sweater lady" static discharge incident. I do turn my engine off, but I usually leave the generator running.

Old habits? or are they worried that they might not get started again?Did a Google search and found the following:The better question is, why are gasoline engines shut off when refueling. The reason you shut off a gasoline engine while refueling is because the vapour that is released from gasoline is highly combustible (hence, how the engine works) and even a small spark (like that from a spark plug) can cause an explosion. Diesel fuel does not "ignite" like gasoline, but rather an explosion is caused by the fuel being compressed to a point that it explodes. This means that it is safe to run a diesel engine while the fuel tank is open. As with all engines, the majority of wear and tear on a diesel engine happens upon starting the engine, so avoiding that step can actually conserve fuel and preserve engine life.Diesel engines can be difficult to restart, especially in extremely cold weather, and the diesel fuel will not perform properly if the engine and/or fuel cool down. In extremely cold climates, truck drivers leave their trucks at a low idle all night to prevent freezing.

Gasoline has a much higher vitalization rate than diesel causing the chance of fumes being ignited by any electrical source like the spark plugs or even static electricity.

I can think of no "Con" of turning your engine off other than if you have just had to jump start your vehicle and the batteries are weak. I think the risk of a running engine starting a fire is not measurable, but not having to breath the fumes while filling should be reason enough to turn it off.

Do you turn off your engine at the gas station?

onebull
Explorer
Nov 29, 2014
No.
JetAonly
Explorer
Nov 28, 2014
http://www.chevron.com/documents/pdf/MotorGasTechReview.pdf

This is a bit of a long read but the discussion on vapor pressure at the beginning applies.

http://www.docs.citgo.com/msds_pi/AG2DF.pdf

Section 9 of this reference gives the vapor pressure of diesel.

XLS fuels comparison

This document give comparisons between fuel, flashpoint and vapor pressures.
mike_brez
Explorer
Nov 28, 2014
What a waste of bandwidth
noteven
Explorer III
Nov 28, 2014
Heat rises actually, so a gasoline refueling fire shouldn't be a concern.

Simple precautions to limit sources of ignition while vapor is displaced out of the tank are overkill.

This is not a problem if you get a diesel, and better yet get a dually because you park farther from the pump.
Sprig
Explorer
Nov 28, 2014
holstein13 wrote:
Not that I'd want to inject any logic into this heated emotional discussion, but I'd go even further and ask, why not require that all cars be turned off BEFORE arriving at the pump and then be pushed in to position and pushed out before starting their engines? ... If we are concerned about running engines causing fires, shouldn't we prevent all running engines near the pumps?

^^^^^THIS!!!!!

In fact, in most cases (especially with autos), the fill is at the rear of the vehicle. Thus if at the forward pump, an arriving vehicle to the aft pump would have it's running engine several times times closer in distance to fueling vehicles engine. Why would this not be that many times more dangerous?

On my well maintained vehicles (gasoline even), I consider it likely safer to leave the engine running. The starter is a great source of sparks, and is typically mounted at the bottom of the engine; as in closer to where a fuel spill would be.

It would probably not even be that unsafe to leave the water heater and refer burners on. Consider just how much vapor would have to be in the air for it to ignite. If there were that much vapor, I would not want to be outside inhaling it.

If one does want to leave their engine running, leave an occupant in the vehicle or take the door key separately. Obviously this is for physical security.

Realize that on some vehicles this may set a computer fault code for the tank losing pressure.

I'm sure there is a law against common sense somewhere; so please don't bother to remind me.
bfast54
Explorer
Nov 28, 2014
okay ----I'm going to have a little fun with this 1 :W

What you need to do is take your white motorhome -------to ferguson and park it in the gas station at night -----and leave it running while you Fuel......at a Convenience store :E:E

What about that 1..........:h

(Lighten up,,,,Francis)......
down_home
Explorer II
Nov 28, 2014
.......
John_S_
Explorer II
Nov 28, 2014
Pop-Pop C wrote:
While traveling, I start the MH. in the mornining and shut it off when I reach my destination.
IMHO Fuel is still cheaper than starters and batteries.

What he said.
Ductape
Explorer
Nov 28, 2014
As I see it, the ability of the fuel to be ignited is a constant. IMO gasoline is the one to focus on since it is easier to ignite, and it's commonly present very near the diesel pumps anyway.

The variable in the experiment is whether the engine continues to idle, or if it is shut down and then restarted. Is one of those variables more likely to ignite gasoline fumes?

Is it possible the rules against idling are more effective in preventing inattentive drivers from driving away with the nozzle in the tank than in preventing ignition per se?

Most driver safety programs will attempt to ban idling with the drivers out of the vehicle as a general safety measure. A lot of things can happen with a running vehicle unattended, most of them bad. I worked for a company that banned leaving keys in electric golf carts because of runaways. Not because we were gassing them up!
JetAonly
Explorer
Nov 27, 2014
http://epa.ohio.gov/Portals/41/p2/HC2web.pdf

"The flash point of a material is a good indicator of how likely it is to catch on fire if there is an ignition source nearby. At the flash point, the material will have just enough vapor available to support a flame. The lower the flash point, the more of a fire danger the material is

Gasoline is the most dangerous with a flash point of about - 45o F. Kerosene is the next most dangerous with a flash point of about 100o F. The flash point for diesel oil and home heating oil is about the same, 125o F."

Hence, there is a difference in fueling risk between gasoline and diesel.

Forum Discussion

Do you turn off your engine at the gas station?

About Motorhome Group

Related Content

Engine won’t turn over

gas stations

Engine torque

Turn signals

Weigh Station Protocol