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      07-13-2010, 08:00 AM   #33
tranquility
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Drives: 2011 Z4 sDrive 35i
Join Date: Aug 2007
Location: Montréal

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Quote:
Originally Posted by teagueAMX View Post
You been doing a lot of research, reading the threads, etc., so you may already be aware of this, but the 35i/35is have two fuel pumps: a lower pressure pump in the fuel tank (LPFP) and a high pressure fuel pump (HPFP) mounted on the n54 TT engine. The fuel tank pump is directly behind the seat. m999psw is noting that while testing his car the dealer managed to use most of the fuel in the tank, which is detrimental to electric fuel pumps. They need fuel for lubrication and cooling. It's a good idea not to let them get below a quarter tank.

The HPFP is the more infamous of the two, but really both are having issues, just not at the same rate. The problem he noted feeds into my theory about why some of BMW’s fuel pumps are failing at high rate. Note my little diatribe here.

http://www.xbimmers.com/forums/showp...6&postcount=57

http://www.xbimmers.com/forums/showp...9&postcount=59

The entire thread

http://www.xbimmers.com/forums/showt...56#post7579356

Don’t get me wrong, I think BMW’s are fantastic cars, but they have an issue with quality control in a few areas, but don't worry you made a good choice buying a Z4!

PS - and don't get caught up in the fuel pump failure related to fuel quality argument!
Thx. Ya, I went in knowing about this and (knock on wood) think I don't have the dreaded HPFP prb but the LPFP supposedly. I'll let you guys know my diagnosis.

It's a bit weird to have a prb since I'm just 3 days new but I'll take it w/ a grain of salt. Right now, it's just a noise issue, so I'll go from there and see what happens (hopefully not much else!). It comes and goes.

One thing I'm confused about is why should we care about the level of fuel in the tank? I should be able to fill up whenever, whether it's 3/4, 1/2, 1/4 or less. Is there anything official from BMW re this fuel level issue?

The car itself has been great but I know I should get rid of those RFTs as soon as they're worn out...can't seem to get much traction on them during spirited acceleration.
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