Dreaded "30 Mile" Gas Range...

[maddad]

I think this is due to the High Pressure Fuel Pumps and injection system. I think they are much more susceptible to contamination in the fuel.

R.

[MikeCCrutchfield]

Originally Posted by pit1

Agreed, "damage" is directed toward the dirt and grime that is inevitably sitting at the bottom of your tank. That's what fuel filters are for, if you make a habit of running low, consider replacing the fuel filter more frequently.

You do all realize that fuel is picked up at the bottom of the tank, so if there is something at the bottom of the than it will get sucked up anyway. Cooling and the chance of sucking air are the reasons not to let the tank run too low (depends on the car for the cooling part)

[EmeraldRx]

Why is it more expensive to get gas? You only pay for what you use? Im I missing something?

[imported_mega]

all I know is you guys that go down to 30 miles would die in the midwest on some country road when it's -20 degrees and a white out blizzard

maybe growing up in those conditions is what trained me to never go below 1/4 tank

[KeithLM]

Originally Posted by MikeCCrutchfield

You do all realize that fuel is picked up at the bottom of the tank, so if there is something at the bottom of the than it will get sucked up anyway.

The idea behind this that I've heard is that the stuff floats in the gas, and so if the gas gets low then the fuel pick-up can suck it up. I'm not saying I believe that, it's just what I've heard.

Granted, this is something I've seen debated a lot. And I can't help but wonder if anyone has actual evidence of a fuel pump burning out from running near empty a lot or from problems caused by contaminants.

[Xyloft]

I think they are trying to prevent damage from running out of fuel and causing damage.

think abou thow lean the motor for would be for a few RPM's if you were WOT, and you ran out of fuel. I mean I woulnt *think* the injectors are going to be 100% then 0% instantly. i would think you'd get and airfuel mix in the fuel lines and you'd run dangeriously lean (especially for you 135 folks).

I'm with a few other posters...fill up at a 1/4 especially if you're traveling places where you know you can't get gas.

[CBLW]

What happens if you get air in the fuel line? Is that the absolute end of the world?

[EmeraldRx]

Hasnt anyone ever run out of gas? You put new gas in and the car starts, worse case here is a clogged fuel filter.

[imported_mega]

worst case is not a clogged 180 $ filter

it's 1 or 2 burnt up fuel pumps, and labor dropping the tank and installing them, I do know a couple audi drivers that did it, burns those pumps up fast

I cant even find a price on the front high pressure fuel pump, I bet it's $$$$$$, the rear in tank fuel pump is 280 $

the fuel is the pump's lubrication internally, and cools the tank pump externally, run low on gas the tank pump gets hot, run out of gas, and it runs without lubrication

it's been this way for many years across all brands

[JB135i]

It costs the same to keep a tank full and it does to keep it off empty.

Not sure why it's such an issue just to fill up at a 1/4 tank or so?!

There could also be fuel starvation issues in high-G corners, if the tank is that close to empty, not good.

Imagine needing to get onto an interstate and while coming down the ramp (highish G) you fuel starve and the car dies just as a semi is coming up....

You will be wishing, if you are still alive, that you took a few minutes to fill the tank.

P.S. The economy as a whole is actually not crap. Some sectors, notably real estate/financials(lending) is hurting for sure, I agree with that. Inflation is up a tick but still not terrible, unemployment is still very low, though up from it's lowest point, oil is down from it's high, retail is actually up an OK amount.

Things aren't perfect, but they are a long way from crap, though the Democrat's are surely going to parade the "afflicted" in front of all of us in the next several days.

[rocketpop]

Are you guys getting two warnings, I get one at about 50 miles to go, then it will go aways. I think will get another about 30 miles to go and that one stays on.

[Robert]

There's a fuel filter. If there's something on the bottom of the tank that doesn't belong in the engine that's where it should be caught.

[thesmokingone]

well... your not really wasting more money by not using the extra miles in your tank, you essentially are working with a 12 gallon tank if your getting 15mpg like i do in the city. if you get better mpg then you could be utilizing 12.5 gallons of your tank. i have heard of this logic before( about not running your tank down all the way). I would be surprised if it really caused any problem that could be traced back to it but its probably better if you don't run it down all the way. also you don't have to wait till the computer tells you to fill up to do so.

[thesmokingone]

also my company and many of our competitors have recorded record high profits for the last three years in a row so not all of the economy is crap

[CBLW]

lol What's up with all of the people talking politics? Is this Politico.com all of the sudden? It was a general point. If you want to make the argument today that things are going well, good for you. Good luck with that.

[Gray135i]

If I fill up around 30 miles range, I am often wasting money. Gas prices vary $0.10 to $0.15 per gallon for premium around the area. I try to plan on getting gas in a cheaper area of town as I know I'm getting low. Sometimes this means filling up with a 40-50 mile range, but sometimes it'll get close to 0 range. If I can always fill up for the lowest price available (at a reputable gas station) that saves me money. I've got maybe 7500 miles on the car so far. If you figure 22 mpg average at $0.10 savings per gallon, I've already saved $30-35 since I got the car. This may not seem like much to most people, but it's these basic math skills that save me thousands of dollars each year in my life.

I think the bottom line comes down to using common sense and don't run your car out of gas.

[jkp1187]

Originally Posted by CBLW

lol What's up with all of the people talking politics? Is this Politico.com all of the sudden? It was a general point. If you want to make the argument today that things are going well, good for you. Good luck with that.

I agree, if I wanted to talk about Politics I'd go to...

Bimmerfest. They always seem to talk about politics there. Cars not so much.

[jeremyc74]

The danger with this car is starving the engine while under boost and going lean before everything shuts down.

Running a modern car to empty isn't going to burn up the fuel pump (at least not a normal one). This was an issue on early in-tank pumps and everyone now swears by it. They figured that issue out long ago.

I run mine down to the very bottom on nearly every single tank. I stay away from WOT once the warning comes on.

[BForbes]

Originally Posted by Tuned1

I always run it down to 10 miles or so before filling up. I've done it with all my cars in the past too.

Me too. My father does it as well. It was a habit passed down from generation to generation. We all drive from F straight to E. We havent run out of gas yet. :knocks on wood: Drives my mother nuts!

[Andys120]

No one has mentioned that it's a good idea not to let the tank run low in cold weather when condensation is most likely to form in the tank. This condensation could lead to frozen fuel lines, rust in the tank etc. I recommend filling in winter if the level drops below half.

Almost all manufacturers recommend not running the tank low in winter. Adding dry gas will help.

If the cost of keeping gas in it is that much of a problem you are driving the wrong car.

[jeremyc74]

Originally Posted by Andys120

No one has mentioned that it's a good idea not to let the tank run low in cold weather when condensation is most likely to form in the tank. This condensation could lead to frozen fuel lines, rust in the tank etc. I recommend filling in winter if the level drops below half.

Almost all manufacturers recommend not running the tank low in winter. Adding dry gas will help.

If the cost of keeping gas in it is that much of a problem you are driving the wrong car.

That shouldn't be an issue on modern cars. They don't use an open vent system.

[crzy4135i]

Originally Posted by mega

the fuel cools the pump, it's suspended with a pickup below it

when the fuel tank is low, the pump is above the fuel and not cooled nearly as good

I try to never go below 100 mile range, that's just over 1/4 tank

That theory applies to just about every car on the road. The in-tank fuel pump can run hot but it will last longer running cool, which requires you have enough gas in the tank so the pump is submerged.

With very low level of gas it can slosh around when you turn and the in-tank pump could suck air intermittently, unless BMW has some sort of baffle around the pickup. It won't ruin the pump right away but it sure isn't good for it over time. What I don't know is what it does to the expensive high pressure fuel pump at the engine.

I agree it's OK to run the tank very low if you're stuck between gas stations.. but don't make it a habit every time.

A few people out there are ignorant enough to believe they're somehow saving money by squeezing every last mile out of every tank of gas. A lady said something like that at a party and I was smart enough to hold my tongue.