Cutting it close with gas today.

[taylorsjt]

I have no such worries, the force is always with me.

[skierman64]

Originally Posted by BigHat

2. Taking the undiluted crap at the bottom of the fuel tank into the system.

Bottom line is that a refill is coming very soon anyway, why not just stop and get gas.

I've heard a few people that are concerned with the "dirt" and the bottom of the tank when running the tank low.

My question is, if the pump is at the bottom of the tank wouldn't it suck all the stuff off the bottom of tank anytime the engine is running, therefore there would never be an accumulation of stuff?

I've never heard of anyone having a fuel problem caused by running the tank low (except of course running completely out of fuel)

[Richbot]

Lots of myths out there about running the tank low, mostly perpetuated by people who have very little understanding of how a fuel system works. The reason most manufacturers recommend filling when the light comes on (and set the light very conservatively) is to avoid a dry pump. For instance, my tow vehicle's fuel light comes on when I have nearly 8 gallons in the tank, and distance to empty reads zero at 6 gallons, on a 35 gallon tank. When the light comes on you have a range of over 120 miles to empty when you're not towing, or less than 50 if you're towing in hills or windy conditions. You can see why they set it so conservatively, and the M3 is no different. It can get 22mpg on the highway or 13 mpg on a deserted backroad or in the city.

Most fuel pumps aren't submerged once you've burned off about 1/4 tank. The only "cooling" comes from the liquid flowing through the pump. Water is heavier than gasoline, as is most "crap", so it's going to be near the pickup anyway regardless of how much fuel is in the tank. There's a filter on the end of most fuel pumps that keeps that "crap" out of the pump anyway. A dry pump can cause the pump to overheat, although most pumps are not running all the time and once the car stops running, the pump stops too. A bigger issue with running the pump dry is air in the lines, which can cause a lean condition and/or a vapor lock in the lines leading to starting problems, catalyst failure, or possibly even engine damage. Fuel injectors are just solenoid valves, they aren't "lubed" by the fluid that flows through them. If they were, they'd be leaking into the solenoid, which would be bad.

DTE when I got to the gas station was 3 miles, and it took 16.071 gallons. Looks like we have, at a minimum, half a gallon remaining when the range readout gives the --- reading. That tank was 19.9mpg, by the way.

[Bokke]

Originally Posted by skim

you could have saved $2.62!

+1

[david @ eas]

Originally Posted by Dustin@AEperformance

I take it below zero miles almost every tank! When I fill up it usually take 16.2 or so gallons.

Your fuel pump probably hates you lol.

Once I hit 50 miles left until empty I fill it up right away, not taking any risks here. I think once, maybe once, I took it to about 15miles left on the tank, but that's probably the lowest

[crazeone]

gas miles are amazing vs a m6 that is the ultimate bmw gas guzzler

[Sandye90m3]

A couple of weeks back I was running really low on gas from a trip back at home. I thought I could be a "Macho" and go without filling up, and I did indeed make it home. Then I went to go fill her up, and the gas station is about 4km down the road and the car started to hiccup right when I entered the gas station and there was completely no power and the car was shaking vigorously. I filled up gas and I think the gas tank is 63L? Well i filled up 65.1L of gas =/ I guess I learn the hard way haha, but I learned well!!

[GregW / Oregon]

Originally Posted by Serious

the tank is 16.5 gallons but that doesn't include the fuel filler neck, which is how you can get it to over 17.

Splitting hairs, but the manual says 16.6 g (hey, 0.1 should be good for 2 miles if you take it easy!).

[TheRealOrosie]

Originally Posted by spyderco10

yeah how do we know a gallon really equals a gallon?

exactly.

[WillC310]

Originally Posted by P-TownM3

exactly.

The dept of weights and measures is supposed to check all gas stations regularly. If they are found out of compliance the get fined.

[FruitCake]

Originally Posted by WillC310

The dept of weights and measures is supposed to check all gas stations regularly. If they are found out of compliance the get fined.

Unfortunately there are too many gas stations and too few people to check, therefore even the Chevron we have in PV has not been checked in many years

[LateBraking]

The things you learn....very interesting guys, thanks. I honestly hadn't thought about the possibility of the station's numbers being off.

[fullrev]

Been at --- with my 335i.... scary feeling.