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Old 01-02-2013, 02:50 PM
Supercourse Supercourse is offline
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Location: British Columbia, Canada
 
Join Date: Feb 2008
Posts: 3,084
Mein Auto: 2004 X3 2.5i
Quote:
Originally Posted by babo View Post
............ on a hot ( 100F) day after driving for about 40 minutes. After 10 minutes stop car could not hold RPMs stable and basically was dropping rpms unless i had accelerator down

..... noticed that when the gas tank is close to 0 ( needle is on the last mark) car tends to vibrate and rpms (while not driving)

...... I have to note that vibration and variance in RPMs don't happened everyday. At this point it looks like they happened @ will or (maybe?) when the gas is very low.
Lots of possibilities I suppose.

Don't think vapor lock is a factor with most cars these days.

Could be the first signs of a failing fuel pump (not a common problem with the X3).

Not sure about running with the gas gauge needle close to the stop.
The Owner manual has something to say on that (attached).

Applies to any vehicle, of course, but best to avoid sucking any bottom of the tank sediment up into the fuel filter by gassing up as soon as the light comes on.

Not always possible or convenient, of course.
Or you pull in to fill up and see a tanker truck is in the process of filling up the station's underground tanks.
Best to avoid buying gas when that's happening as their storage tank is getting stirred up.

Used car dealers tend to understandably keep low gas levels in all their cars and just splash in a gallon for test drives.
That can't be too good, and if a car stays on the lot unsold for months with little fuel in the tank some rust may be accumulating.

Replacing the fuel filter in an X3 may not be an easy or inexpensive job, but in some cases might be well worth doing.
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