As far as I know, if they are sure that the pump itself is the problem, then they don't need to replace all those parts. But if they are unsure of the exact problem, then they're probably trying to cover all their bases and hoping covering all of them solves the problem the first time around.
If the left level sensor or the sucking jet pump has a problem, then you should either be running out of fuel before your gas gauge shows empty, or not be able to put in a full tank's worth (15-17 gallons) when you fill up from empty. If it's the fuel baffle fixture then your car would be choking/stalling/losing power under hard cornering when it's light on fuel (think autoX). However, any one of these could cause a problem with proper fuel delivery to the engine, and might create the symptoms you describe. It's hard to tell without actually experiencing it in your car. Hopefully the BMW techs did experience it first hand.
how many miles on your car?
Last edited by AllwaysLow; 08-03-2009 at 10:42 AM.