Might not hurt to run some fuel injector cleaner too, now that I think about it. I've had good results with Techron and BG44K.

 

My only thought on this would be that maybe with a plugged up sock, the pump can't maintain the fuel system pressure or flow that the injectors are designed for. So you don't get a fully atomized spray and you don't get as complete fuel burn. Then its kind of similar to a dirty injector. You end up using more fuel because the PCM has to put in a larger duty cycle on the injector to burn the same amount of oxygen.

Seems reasonable (sounds good in my own head at least), but also seems like the sock would have to be pretty well plugged though.

 

Well 18 mpg is about average. I highly doubt you were getting 25 mpg before. I think your starting numbers were off. If you leave the mpg computer alone for a tank or two it will give you an accurate reading. What does your average speed say? I can see getting 350 miles on a tank if you run the 15-16 gallons through it and you're on a road trip and run the whole tank on the freeway cruising at 60. That would put you around 23 mpg which is not unheard of for a freeway cruise. But you are right around where you should be so i would chalk it up to bad starting numbers. /i mean that 350 mile tank was probably your highest one ever. you can't use that for comparison. I do mainly freeway driving to and from work and my avg speed is always around 30 mph. I bet yours is pretty close to that. Again, do that calculation over some time, not one day.

 

Nope, not close, but a good reach. If the fuel was restricted at the pick up, the pump duty cycle would increase to maintain pressure, and if it couldn't you would have a CEL. If not enough pressure is available at the injector it would run lean and increase mileage anyways. Yes the car would try and add fuel to compensate but you still wouldn't run rich. The computer will make small adjustments but it will not change mileage by 30%.

 

It was a reach

 

ha ha, don't overthink it, you might outsmart yourself

keep it simple: anything that interferes with the car running at the most optimum, can reduce fuel efficiency. It seems like restricted fuel filter might make it run lean if anything . . . but that is not going to be as efficient.

So it's always a good idea to just do all the basic maintenance first (which is usually relatively cheap) before chasing gremlins.

 

Well the OP has done all of that. I don't think he has any gremlins. Just don't think he's comparing apples to apples. Miles per tank by itself is not a good way to calculate usage. I don't think he was getting 350 miles with 13-14 gallons. Maybe 16 gallons on the freeway but no way was he getting 25+ mpg doing daily duties.

 

Speaking of which, Mike, any improvement yet? What have you tried so far?

 

actually I cleaned the MAF with some special spray I got at kragen. Now my mpg is a lot more active and fluctuating. I haven't run a full tank through it yet so I don't know what I will get. As for my previous posts, I should say yes that 350 miles out of a tank was mostly freeway and 300 was kind of the norm but 200 is lately. Anyway I'm interested to see how this tank will run out.