Contour Enthusiasts Group Archives Forums General Troubleshooting Bad fuel mileage after fuel filter change?

I recently changed my fuel filter on my tour and noticed a drop in mileage. The motor seems more smooth...a little but I notice my gas needle is dropping faster than before the filter change. It has been 3 weeks consistantly and I have been light on the throttle. There are different way's of changing the filter..is any way going to give different results. I didn't depressurize my fuel system like recommended but was told it didnt really matter. Should I have and would there be a way to correct it. Thanks in advance for any reply's

Have you logged your actual mileage, or are you just guessing based on your guage. Also, all you are doing by de-pressurizing the system, is making less of a mess, as well as being safer! (I think). Just a guess, but is the filter facing the right way? This might be ths issue, but not real sure. Check it out....

You probably have a leak! Do you notice any drip marks on the pavement or gas smell?
Other than that, I don't think your mileage can get worse by simply changing the filter.

Did you reset your PCM? Usually if your filter was somewhat clogged, the PCM learned to increase the fuel intake to insure you had enough fuel coming into the intake and allow the correct combustion to occur. Now that you have replaced your filter and fuel flows freely, the PCM is still using the past learning mode to conduct combustion, thereby increasing your fuel usage. This would mean that your engine is running richer. Eventually, it will re-learn not to do this, but it takes a while to learn.

Also, after you have verified the other suggestions given in these posts and if you do not see any results from the corrective actions suggested, you may want to check your EGR passages around the throttle body mating area. What I learned is that if your fuel filter has not been changed for a while, and this area gets plugged with carbon, the PCM adapts to all these different parameters to make sure your engine is still running smoothly but not in the most efficient manner. Once you change one of the components that it has learned to compensate for, it will still continue to compensate for it and will not run too well cause you just changed something too fast for it to try to learn to cope with over night. In my case, I had to clean out the EGR passages too, they were plugged, so it could re-learn the correct parameters and give me back my fuel efficiency. Just something to think about if your efficiency does not return after you reset the computer, etc...

Tell u the truth about that try using some fuel inj. cleaner for the car..dirty filter also means dirty inj.

Thanks for the reply's.
Resetting the pcm makes sense as does the others. My mileage has dropped about 40 or so miles a tank or about 2 mpg or so. I will try to reset the pcm. I just hate the fact of resetting the pcm every time something changes. My engine has to relearn ...my tranny has to relearn but I guess thats the point of it. I did change the filter at 44k so maybe it was really dirty and the pcm was increasing flow to compensate like said earlier. The thing that caught my eye early on is that the gas needle falls off of the "F" alot faster than it used to.
Thanks again

Another possibility is that your region has changed over to winter grade fuels, coinciding with your filter change. I have noticed a difference here in Houston when they do that. In fact about 2-3 mpg difference is about right for the fuel change over.

Don't know what your explanation is, but I've certainly changed my filter a number of times without mileage change. In fact, my mileage has slightly but steadily climbed over the years 97-01. Good luck!

raydeeo,..well thats what I expected with mine but based on your mileage and having done it several times, maybe yours never got a chance to "clog". I'm at 44k and changed it for the first time. I'm hoping a reset might help it out. Unfortunately, I wont notice the difference for at least a week or so(till I calculate my mileage on a tank.
I know there is no leaks. I have felt the line and its very dry and not a scent of gas.

Also suggest not trusting "miles per tank" method. Divide miles between fills by gallons to fill. Even then you can't quite trust a single calculation, but have to average a few.