Originally Posted By: dparm
A lot of guys knee-jerk and say you should replace it if your car is stumbling or feels sluggish. I don't understand why. I've never seen a fuel filter look clogged or dirty.
I changed my old Audi's fuel filter at 50k and it literally looked brand new.
Your Audi's fuel filter may have looked clean, but that doesn't mean that it should not be serviced. That means you were lucky and either didn't have much crud in the tank, or the pump hasn't picked it up yet. You did the right thing changing it, if the manual recommended a 50,000 interval.
Over the years I have personally seen fuel filters clogged to the point that the vehicle ran poorly. I have seen vehicles towed in with a bad fuel pump and a clogged filter. Clogged filters are a real problem, not just old some old wives tale. If there was no need for fuel filters you can be sure the manufacturers would not put them on and would pocket the savings.
Now with that said, contaminated fuel is not the problem that it was years ago and clogged filters are not as much of a problem, but it does still happen.
If a vehicle has a drivability problem and the filter hasn't been changed on schedule, or not at all, it makes sense to replace it, as maintenance, and as a diagnostic step. How long do you think a mechanic would last in a repair shop if he spent hours searching for a stumbling issue and the fix was just a filter replacement ? I've seen that happen.
The advice to start with a new fuel filter when diagnosing a drivability issue is still good in many situations, especially when the filter is about $20 or less.
Think about this, a pump will continue pumping even if a restriction is placed upon it, like a clogged filter. But that pump is now pumping just a little harder. Harder than it was designed for. How many miles will it take for that pump to fail prematurely ? That is correct...who the heck knows. So why introduce a variable like that when there is no need to ? Follow the recommended filter change interval.
It's not like there is one fuel pump used in all cars and that pump has been improved to the point of invincibility. On the road right now there are hundreds of different pumps and they all have a point at which they will fail. Which pump do you have ? One that will last forever, or one that will fail at the first sign of restriction ahead ?
Who knows ?