I'm having some MPG issues too. 13.5-13.9MPG driving like a granny around town. Bought some plugs and will replace them tomorrow hopefully. Seafoamed, changed oil and everything. Should I check my O2 sensors on my 2001 XJ. I'm at 89000 miles

 

2001 stock XJ about 66K get about 18.5 mpg (I spend most of my time on the highway).

Here's my spreadsheet you need the new (vista) version of excel for it to work.

 

i keep seeing fuel filter. if this 2001 is anything like my '98 its the fuel pressure regulator and filter in one unit. have to drop the gas tank to change. PITA in the rust belt. part from dealer was like 110 bucks, internet ebay 40 bucks. i bought both actually. wish i would have checked ebay first

 

if you do get the issue straightened out I'd love to know what finally improved your gas mileage. i just bought a 95 cherokee and i'm having the same issue with it, except i'm going about 170 to a tank if i'm lucky.

 

I will let you know as soon as I do. It seems my fuel pump is going out, and mixed with the fuel pressure regulator and filter I could see why it caused my bad gas millage and starting and running issues.

 

UPATE: I took it to the school to let a friend check to for me because he has accress to all the tools. With it running and the guage hooked up the the pressure testing screw in on the fuel rail it apparently came out at 46 psi. I know this means something is wrong.

I talked to my friend and he said the teacher kinda messed it up and didnt know how to do it right so I plan on checking it myself.

 

i only have gas mileage problems when I LET THE FIANCE DRIVE