My E34 is lying to me

Your car is probably bent in half from dragging that damn trailer, and the last gallon of gas is stuck where the sending unit can see it, but the pick-up can't get at it.

The Low Fuel light seems to be working right to me, you ignored it's warning and now it is explaining why you are walking. If it said that you sitll had

100 miles remaining, then I'd wonder what's up, but you got down to within the last gallon of gas remaining.

The OBC is not that accurate. When the low fuel light comes on, it's best to put fuel in it.

I usually fill up when I get down to 1/4 tank. This applies to ANY car as it keeps me from getting sidetracked and having to push.

Like your speedometer & "Dubya" - maybe we should all start to worry!

Tom

I take it you're not a rocket scientist?

I once ran my E39 to 5 miles from empty on the OBC - and a long time after the light had come on. And it took the stated capacity of the tank to fill it.

So I trust mine. The E39 IIRC has twin fuel level sensors. Dunno if the E34 has.

Nah, my car is fine. Ready to pull another trailer... :-)

Well, I think that if the OBC is unable to correctly calculate the distance it should err on the safe side, and not overestimate it.

Ulf

Is that a requirement owning a BMW?

Ulf

It probably worked fine when the car was new, but it't getting on in years, and there was trouble with the gas a couple of years ago that made fuel level sending units go haywire. I don't remember where you live, but the bad gas was all over the southeast and up the eastern seaboard. It would be nice to have a device that knew precisely how much fuel remained, but there are just too many variables to deal with, and time is among them.

The OBC gets one very important piece of information externally to determine how much further you can go. It gets the fuel level from the fuel tank sending unit. It takes that level reading and calcul;ates how far you will be able to go based on an average of your recent mpg calculations. If the sending unit lies to it then the OBC will also lie to you.

As an aside, it's generally considered a bad idea to run your tank so low. Aside from having to walk, it stresses out the fule pump. You probably don't want to make a habit of that...

-Fred W

It is simple, Ulf. You are a dumbass AND you have bad gas.

If you run your tank real low you also risk sucking up some of the shit that sits in the bottom of most gas tanks and clogging your filter or damaging the pump itself.

Steve

I have run my car to "0 miles left" but had not run out (but close!)

DAS

For direct contact replace nospam with schmetterling

Calling people names only reflects on the caller. If the OBC indicates many miles to go it is not unreasonable to be able to go at least another few miles.

Having done experiments on my car (spare 5-l cannister in the boot!) I know I can run my car down to 0 miles left without running out, though I would not try it on a regular basis.

DAS

For direct contact replace nospam with schmetterling

I thought it was common knowledge that running your car to almost empty is not advisable. If the OP was not aware of this, then he is now. If he was aware, then he's a mute posterior.

I just don't understand why someone would run their tank to almost empty, just to save them from having to re-fill a hand-full of miles sooner next time.