Dirty fuel filter hurt MPG?

[Cos]

I have been stalking my F150 forums and one of the fixes for low MPG they suggest is to change out the fuel filter. Maybe there is someone on here smarter than me who can explain this.... but how does a fuel filter being dirty hurt MPG? If the fuel filter is plugged wouldnt less fuel be getting through? If not that the only motor you are really working is the fuel pump so you could be jeopardizing it but not the motor?

Help?

[GQBalla]

your logic makes sense about less fuel getting in, im not sure btw.

BUT i do know whenever i change the fuel filter i get a increase in fuel mileage.

[Cos]

Originally posted by GQBalla
your logic makes sense about less fuel getting in, im not sure btw.

BUT i do know whenever i change the fuel filter i get a increase in fuel mileage.

Yeah that is what these guys are saying too. Maybe fuel filters are bypassed so they dont starve the engine giving it dirty fuel. I guess I should change mine.

[GQBalla]

i think it would have something to do with the amount of fuel used to get up to speed or something

[CapnCrunch]

If you aren't getting enough fuel your truck isn't running it's optimal air fuel ratio where it makes the most power (ie: where your engine is at optimal efficiency.)

[Zero102]

There are 2 arguments to present here:
1) If the filter is VERY dirty, such that it is restricting fuel flow enough to bring the fuel/air mixture way out of the optimal range then it can hurt the efficiency of the engine. Since your engine is always working less efficiently but you are asking for the same amount of power from it, you will always consume more fuel to produce that power
2) If the filter is only slightly dirty, it can have the same effect as being a little bit lighter on the right foot and actually improve fuel mileage.


In every case where I have changed a fuel filter to resolve an issue, I have been in the second case and my mileage has gotten worse as a result. That said, I am sure there are many people in the first case and fuel mileage may improve from changing the filter.

[V8 LOL]

Chances are it could be running way richer even though less fuel is actually getting through

[Kavy]

Originally posted by CapnCrunch
If you aren't getting enough fuel your truck isn't running it's optimal air fuel ratio where it makes the most power (ie: where your engine is at optimal efficiency.)

QFT

[spikerS]

alot of people don't seem to realize that it is not the RPMs that dictate how much fuel you use, but how far down you press the gas pedal (open the throttle).

With a clogged or dirty fuel filter, you restrict the gas flow, thus to get the same acceleration or cruising speed, you have to increase the fuel flow, and that is usually done with an increase of pressure from the fuel pump. a clean filter requires less pressure, and thus the throttle is open less.

I don't think I explained the above quite right and someone will correct me and make fun of me I am sure.