[Sindarin]

Originally Posted by roundel335

Both pumps are electric and have to be running before the engine starts.

No. The low pressure in tank fuel pump is electric. The high pressure fuel pump is mechanical and runs off the engine.

Originally Posted by roundel335

Unless you shut the ignition off completely, they will continue to run, fuel or no fuel.

No. The low pressure electric in tank fuel pump will prime for a few seconds when the vehicle is woken up then will shut off until it sees a crank signal. The high pressure fuel pump is mechanical. If the engines not spinning its not generating any pressure.

Originally Posted by roundel335

And when that happens, the HPFP will fail first. If the LPFP fails - whether or not there's fuel in the tank, the HPFP will also fail if the ignition is left on.

WTF? How can the high pressure fuel pump fail if its not even moving?

Originally Posted by roundel335

Walk up to your car after it's been shut off for an hour or so - the minute you unlock or open a door, you hear the LPFP run as it primes the HPFP.

This is the only thing that I kind of agree with.

Originally Posted by roundel335

When you switch the ignition on, the HPFP primes the injectors at 25,000 PSI - otherwise, the engine won't start because there's no fuel being sprayed into the combustion chambers.

No. The high pressure fuel pump is mechanical so its not generating any pressure until the engine starts spinning so turning the ignition on isn't priming the high pressure fuel system. Secondly the high pressure fuel system in BMW gas engines only operate at a max pressure of 200 bar, or 2,900 PSI. Diesels can operate at those pressures but if you saw a diesel high pressure pump you'd understand why.

[EEBreh]

Why risk sucking the crap from the bottom of the tank through your fuel filter (thats not replaceable) and also risk messing up an expensive hpfp? Fill it when its 1/4 of a tank. I have two other german cars from the 80s and I'm still surprised about the amount of crap that gets caught in the filter.

[3.0L]

Originally Posted by EEBreh

Why risk sucking the crap from the bottom of the tank through your fuel filter (thats not replaceable) and also risk messing up an expensive hpfp? Fill it when its 1/4 of a tank. I have two other german cars from the 80s and I'm still surprised about the amount of crap that gets caught in the filter.

The pump picks up fuel at the bottom of the tank. Makes no difference whether the tank is full or nearly empty.

The fine mesh fuel filters between the tank and engine are replaceable.

[Groby Gruger]

Originally Posted by morphomeman

We need to hear from someone who has run out of gas in a recent-model BMW. Has it gummed up the works in some way?
And, BTW, if you run out of gas, does calling BMW have any effect?

I ran out of fuel a few meters away from a petrol station in my M235i. The car threw up an error on the dash and I even tried to restart the engine a few times . Highly embarrassing but once refueled it was as if nothing had happened. Error code went, and there wasn't any appreciable difference in the performance or sound from the car. I didn't call BMW so can't answer the latter part of you question.

Hope that helps.

[Zandar]

Life philosophy: Reload when you can.

It applies to:

• Refueling you car and/or boat

• Charging your phone

• Your gun

• Meals

[doccyber]

My OCD won't let me go below 1/2 to 1/3. So I have never run out of gas.

[crabu2]

Originally Posted by doccyber

My OCD won't let me go below 1/2 to 1/3. So I have never run out of gas.

Last night when I filled up, it only took 7 gallons..

I really with the fuel tanks were a few gallons larger on these cars. 13 gallons is just too small.

[rich8566]

Originally Posted by aerobod

I've driven over 500,000km in BMWs and somewhere around 1,000,000km in other vehicles and usually refuel when there is less than 5 litres in the tank, I have never had a fuel pump or fuel system issue. I've kept the majority of the vehicles for over 7 years while using this refuelling policy.

Same here. No issues ever when running down to less than a gallon or so left in the tank.

[qnet]

I usually don't let my fuel get below a half tank, it's just the way I like to do it. The only issue I've had, that hasn't been mentioned yet; is when you track the car.

The track were I did my HPDE last year is about a hour from my home. I filled up and drove straight there and did my sessions. I always made it through the day but was very low on fuel afterwards.

On the last session they let us go a little longer and I got a "drivetrain malfunction" message on the I-drive screen. The car lost all power, and I had to pull over and let the car sit. After sitting for a few minutes the car started up, I was able to drive off the track to the fuel pump at the track with the very expensive fuel in it.

I know this is a extreme scenario, since a lot of you probably don't track you car, but think it's good info just in case you decide to. This was my first time at the track and it scared me, but I found out it's common in some BMW's, not just the M235i.

[crabu2]

Originally Posted by qnet

On the last session they let us go a little longer and I got a "drivetrain malfunction" message on the I-drive screen. The car lost all power, and I had to pull over and let the car sit. After sitting for a few minutes the car started up, I was able to drive off the track to the fuel pump at the track with the very expensive fuel in it.

Vapor Lock?

[Maynard]

The downside to the obvious 'keep it full' plan is that I've heard gas pumps retain quite a bit of the gas from the last guy's fillup in the hose mechanism, so even if you pick Super, the first bit is usually regular. Only estimate I've ever heard is that this can be almost a gallon. Thus I try to let it get down to quarter tank first, so I'm not constantly diluting my premium (had considered finding another hi-tech car to follow, but I don't have the patience to sit, and figured I'd get reported for stalking). These tiny tanks really are a drag - I'd drop serious $$ to step up to a 20-gallon.

And I'd love to hear that this is bogus, from s/b who really knows how the pumps work.

[3.0L]

Originally Posted by Maynard

The downside to the obvious 'keep it full' plan is that I've heard gas pumps retain quite a bit of the gas from the last guy's fillup in the hose mechanism, so even if you pick Super, the first bit is usually regular. Only estimate I've ever heard is that this can be almost a gallon. Thus I try to let it get down to quarter tank first, so I'm not constantly diluting my premium (had considered finding another hi-tech car to follow, but I don't have the patience to sit, and figured I'd get reported for stalking). These tiny tanks really are a drag - I'd drop serious $$ to step up to a 20-gallon.

And I'd love to hear that this is bogus, from s/b who really knows how the pumps work.

Gas station fuel dispensers have the capability to draw from various under ground fuel tanks, including mixing different octanes. I can picture the valves inside the pump mechanism and I cannot imagine how a gallon of fuel could be trapped in there.

Also, it's a crap shoot as to what grade of fuel was dispensed before you arrived - not automatically regular grade. Frankly, I wouldn't lose any sleep over it.

[crabu2]

Originally Posted by Maynard

The downside to the obvious 'keep it full' plan is that I've heard gas pumps retain quite a bit of the gas from the last guy's fillup in the hose mechanism, so even if you pick Super, the first bit is usually regular. Only estimate I've ever heard is that this can be almost a gallon. Thus I try to let it get down to quarter tank first, so I'm not constantly diluting my premium (had considered finding another hi-tech car to follow, but I don't have the patience to sit, and figured I'd get reported for stalking). These tiny tanks really are a drag - I'd drop serious $$ to step up to a 20-gallon.

And I'd love to hear that this is bogus, from s/b who really knows how the pumps work.

When you figure out how to get a larger tank, let me know. 13 gallons is too small.. I could live with 16, but 20 would be the bomb!

With this little stock tank, I think I'm filling up every other day.. 7 gallons here, 10 there.. When you drive as much as I do, over a 100 miles a day, stopping for gas is really a drag... I drove over 200 miles yesterday... filled up yesterday morning and I'll be filling up again today.

Man, I also wish this car also had ventilated seats.. Why does my pickup have them and this not?? The least BMW could have done was perforated the seating surface to allow some air circulation.

[Kolyan2k]

Originally Posted by crabu2

Man, I also wish this car also had ventilated seats.. Why does my pickup have them and this not?? The least BMW could have done was perforated the seating surface to allow some air circulation.

Few days ago got out from a car in blue shorts, looked like I pissed myself. Wife had to do shopping without me time to give baby power some thought ))

[Maynard]

Yes, I'd spend for this before a downpipe or new suspension for sure. If it is any consolation, I think that the British versions are even smaller. At one point I got excited by seeing British options of 'larger tank' but when I finally got reply from the geniuses they tell me that 'larger' for them is just the 13gal. I have not yet taken the time, but may pick through the foreign pages to see if any countries list a larger tank (hope springs eternal...). I'm also wanting to find out if perhaps they fit the tank on the other side for the Brits, or just the filler neck (and if there is room there on our cars that you could mount a second tank). No doubt this would require act-of-god changes to some of the coding too, so probably just a fantasy for now.

[aerobod]

The fuel tank is 52 litres in all markets, it can't be expanded, as it is shoe-horned under the back seat, taking all the available space. The UK tanks / right-hand drive cars are the same saddle tank, with the filler on the right: http://www.realoem.com/bmw/enUS/show...diagId=16_0872 There is an option for an increased sized filler pipe, probably to meet fuel station nozzle requirements in specific markets.

[rightrudder]

Looks like the LPFP can be accessed by taking out the rear seat cushion. My E46 is set up this way too. So much better than a lot of cars where you have to drop the tank to replace the pump.