Low gas mileage

[mk333]

For about a month now I have noticed a decline in the km's I am getting with my Jeep. I have an 2001 XJ and usually can get around 500 km's to a tank but I am getting just over 400 now. I was thinking mabe a new fuel filter might be the answer but maybe you guys/gals here might have another idea. Tires pressure is good, new air filter and doesn't burn any oil. I've been doing the same commute for 3 yrs now..Carstairs to Airdrie every day so all highway km's. Any ideas would be great.

[apeman]

Fuel filter is built into the pump, which means dropping the tank. Have fun.

[JENSSEN]

Have you checked the Cat convertor, O2 sensors, has it had a tune up?

[whitefang]

agree with JENSSEN, check sensors then tune up!

clean throttle body, fuel injectors, new fuel filter
check spark plugs (if one is foiled test coil pack) change spark plugs, plug wires,
check timing.

for best gas mileage, run 215 75 r15 tires stock gears and no lift!!!

[morerpmfred]

Have been doing a commute to highriver everyday as well. Really windy the past month and  a half. Gas mileage in the big work van went way down as well.

[specialk]

Just carry a jerry can..  Or 2...   Its a jeep

[birdo]

Any chance your fuel gauge is out of whack? I would check O2 sensors for sure. They are good for about 50,000 kms then you really should consider replacing them.

[Immortal]

I was getting the same 500km/tank in my 99 XJ, then I switched to synthetic oil, transmission fluid, and gear oil. Started getting about 600kms/tank. But.... Wind played a huge factor in mileage.
I was about 50/50 city/highway driving.

[birdo]

Which reminds me.....I put synthetic in the gearbox last year and it made a HUGE difference to cold weather shifting and gear selection overall. Plus, I got rid of that stupid rubber shifter boot and replaced it with a nice soft leather one. HUGE!!!!!

[mk333]

Thanks for all the info. I ve been thinking about going to synthetic for a while now. Spark plugs and O2 sensor are a good start.