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Old 11-20-2012, 12:25 PM   #458
MJLavelle
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Join Date: Jul 2011
Location: Charlotte NC
Posts: 2,753
My Ride: 2001 BMW 330ci
Quote:
Originally Posted by 76m2002 View Post
I admit I didn't have the patience to read 23 pages of posts! However, one thing to remember is that your in-tank fuel pump is cooled by the fuel, and overheating is an accelerator of pump wear. if you refill your tank when you get down to a quarter tank, you will keep enough fuel in the tank to cool the pump, and minimize the amount of sludge that gets sucked into your pump from the bottom of the tank. 111,00 mile and still on the original pump.
Quote:
Originally Posted by 76m2002 View Post
I admit I didn't have the patience to read 23 pages of posts! However, one thing to remember is that your in-tank fuel pump is cooled by the fuel, and overheating is an accelerator of pump wear. if you refill your tank when you get down to a quarter tank, you will keep enough fuel in the tank to cool the pump, and minimize the amount of sludge that gets sucked into your pump from the bottom of the tank. 111,00 mile and still on the original pump.

Many people mention this every day on here (sorry, you are not the first), so I am not picking on you specifically, but people always give this advice about not running below a 1/4 tank because the pump will supposedly pick up more dirt, but the intake for the pump is in a fixed position at the bottom of the pump. By that logic, it is always sitting in the dirt. I am also not sure what sort of dirt people are expecting to find in the bottom of the tank, but mine was clean as a whistle when I changed my pump. I did not see anything settled on the bottom. The screen was also perfectly clear of debris. It was just discolored, while the new one was bright white. This was after 120k miles. Does anyone have a pic of an e46 tank with a lot of junk at the bottom of it? Can anyone say for sure that they saw a lot of crap in the bottom of their tank?
I can agree with the pump needing to be cooled, so you need to keep some gas in there. But this gas tank sludge is somewhat mythical, and if it does exist, then the intake is sitting in it if you are on empty or completely full.
I know it was a problem a long time ago, due mostly to the materials used to make the old fuel tanks, which would start flaking off or the tank would corrode from the inside out. Also, the old independent gas stations were not the cleanest places either. But with the large conviencence store/gas stations, most of them are relatively new constructions, with relatively new modern tanks to store the gas. I just dont think large particle sized dirt is an issue with our gas any more. Small particle dirt I can believe, and that is what the fuel filter is for. I think this is just something that gets passed around and accepted as common knowledge, and no one really questions it.
Cleaning the wheel speed sensors is another good example of this. They are a magnetic pickup, which is not affected by dirt. That is why they use them way out there near the tires and brake dust and dirt. I doubt there was ever an optical type wheel speed sensor, which is the type that may benefit from a cleaning. If there was, I bet it was not used for long. But people still advise this on here every day.
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