Quote:
Originally Posted by teagueAMX
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!  |
I am impressed by your research on this issue.
I can see from your write up that you have done a lot of work, devoted a lot of time to get to the bottom of this or at least try.
Your theory certainly makes sense and your write up provides readers with the right ammunition to ask the right questions at the dealer. Well done.
I think what needs to be done now is
some follow up to find out how many members (here and on other Z4 forums) to see for example ...
How many members had there fuel pump replaced?
Was it the High Pressure Pump or the Low Pressure Pump?
How many members still have problems after pump replacement?
At what point (milage) the pump failed?
Perhaps you can post a new thread here on this site making reference to your earlier posts on this subject. I am sure many members will appreciate your overall effort on this subject.
Once again I think you made a great effort to find information on this subject and it would be ashamed to now let it idle and not follow up. I am sure you agree the fuel pump issue for the E89 drivers is very important.
Thank you,
Rolf-Dieter