Regardless of retailer (Shell, ARCO, etc.) all gas is generic now days and the particular brand additive package is mixed in the fuel at the last minute, so to speak, just before it’s loaded into the delivery trucks in route for the gas station.

Years ago they were experimenting with non-petroleum based fuels like methanol that were highly corrosive to different types of metals and plastics. However, now days virtually all auto fuel is petroleum based with a percentage of non-petroleum based additives such as ethanol (distilled vegetable based alcohol). This has been the practice for many years and all new cars designed for sale in the US market are designed to handle it.

All that is to say that BMW’s n54 TT in-line 6 cylinder fuel pumps have some type of design flaw. Why they can’t fix it is a big mystery because they’ve had plenty of time. I pile on lots of miles on my cars over a number of years – my current non-BMW car had over 60k mile before fuel pump replacement and the car before that had over 100k miles. My friends have had the same experiences – many trouble free fuel pump miles.

Let’s face it, German cars may be cool, but German engineering is not all that it’s cracked up to be. They certainly don’t maintain the same quality control standards used by the Japanese, notwithstanding the recent Toyota bad gas pedal design. Feel free to disagree with me, but think about it: BMW offers a no cost maintenance program and their sales skyrocket. Now VW is going that way too. Expect the same from Audi because they are basically crap anyway. People may be bored by Japanese cars, but does Honda need to do that? Manufactures offer long warrantees only when they have to. Honda doesn’t because people are not afraid of having to pay huge $’s for unscheduled repairs with a Honda.

“. . .and is now being advised to keep his gas tank above 1/4 a tank to prevent any limp modes.”

One problem with electric fuel pumps in the gas tank is they use the fuel in the lubricate and prevent overheating the pump. The pump is also sensitive to fuel sloshing around the pump pickup that occurs when the fuel level is low. They typically put a canister around the primary pump inside the tank to equalize the amount fuel when making turns, accelerating, stopping fast, because these maneuvers cause the fuel to slosh away from the pickup, causing cavitation and overheating.

Normally you don’t want to run your tank down to empty to prevent problems, but saying you should avoid going below a 1/4 is an admission there may be a tank design issue. If the primary pump runs dry it will adversely affect the HPFP, which could be the basis for the recurring problem.

I’m unsure. I have heard reports both ways but nothing concrete. If I receive word I’ll post it up.

- J

Are the MY2009 E90 335i cars going to get a new fuel pump design from the start of production in September?