As I understand it, there is no build up of sludge in cars such as ours (plus no rust) and yes it would be the first out (and thus end in the fuel filter).

 

Open up an empty tank and take a look at the bottom. You probably won't find much debris, but chances are that you will indeed find a little. Tank sludge is not nearly as much of a problem as it was decades ago. If there was zero debris, there would be no need for a fuel filter....

 

Why isn't it all in the fuel filter?

 

In my experience you can get some debris that will settle and sit in the bottom, as sometimes the baffles in the fuel tank that keep the fuel from sloshing around will also keep all of it from completely draining out of the bottom as well. So even though the fuel out line is at the lowest point, there can be some instances where not all of the fuel makes it to the pickup - and some debris in that fuel will kind of impede it from running to the pickup as it normally would.

I agree far less of a problem than it used to be. However there can still be debris picked up from the fuel itself that is heavier than the fuel and will settle to the bottom, and the baffles will help in keeping it from completely mixing and moving to the filter.

With ethanol cut fuels these days, I'm not sure if phase separation could also play a role in debris suspension or not.

 

Phase separation will only occur if 1) there's more water in the fuel than the ethanol can deal with, and 2) the tank is allowed to remain static long enough for the different liquids to stratify.

Neither is likely to occur on a car.

 

Tell me more about the Mafioso intake. I just purchased 2003 S-type R. It is all black and I did just get tint done which will likely be only cosmetic upgrade, but I am interested to see what would be some first steps performance wise. Thanks for your input!

 

1) Basically, yep. Ethanol is also a solvent and can loosen up any debris that may be in the tank.

2) Possible IMHO - vehicle with perhaps 1/4 tank of fuel stored over the winter months 60-120 days or more. Careless storage method of course so let's hope it shouldn't happen in a car, but possible. But I agree not likely.

But we are straying a bit from the topic (and about at the limits of my knowledge of the matter ) so that's all I got.

 

See the sticky on the first page of the S Type board, or use the search there is a lot of info on this.