My truck had 90+K on it when I changed the fuel filter, didn't need it and thought might as well. It now seems like my gas mileage is not as good as it was. Is it logical to say that with a new filter, gas is able to flow faster and use more cause it is new. I have a heavy foot but was calm for my last trip to Philly from Virginia Beach (297mi od) I topped off the tank before I left and topped it off at 14.7 gals when I got home thats about 20mpg the last time I made that trip with the old filter it was about 22mpg. Is it the filter company or do they all do that.

 

no, it's another factor no doubt, the fuel filter can't flow too much, the flow is metered by the injectors. Was there a large temperature difference? load difference? time between injector cleaning? condition of spark plugs? condition of air filter?

there's too many variables to list, but the filter replacement is 99% of the time not going to be causing worse mileage

 

I would agree with Nick. You could have had a headwind, drafting off of cars, tire pressure, and a million other things.

 

Definitely isn't an issue with the new fuel filter. We could type a novel on all the possibilities.