Poor Mileage

In_the_works

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Anyone have any suggestions as to what could cause a sudden decrease in MPG? I used to get 13-14 mpg, but recently it's been more like 9-10. I cleaned out my air filter and swapped spark plugs, but neither has had any effect. What else should I check? My engine is a ford 351w with EFI and an E40D transmission.
 

1992f150

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same thing happened to me, do a code scan and look for any EGR stuff. fuel filter might not hurt if you havent done it in awhile.
 

In_the_works

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Would I even need to check that? I just had my truck smogged and it was well within the normal levels. If there was an EGR fault wouldn't it have showed up then? Thanks for the advice on the fuel filter though, I'll check that out today.
 

Ryan B

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In my truck my disributor hold down got loose and the timing was way off. My truck was getting really bad gas milage. After I got it timed the milage went up noticably, so you might want to check your timing your timing.
hope this helps
 

Jack

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I'm having this right now also, I have heard that it has to do with the "summer gas" they have a diferent mixture for the summer, it is suposed to make less smog, but the debate is still open.
 

1992f150

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No mine still passed even throwing egr codes. Might as well do a scan anyway.
 
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