hi my truck 99 2500 with 5.9L 4wd is getting 8mpg average over 3 tanks

i average 240 miles till gas light comes on and this is with a 34 gallon tank

this is not towing and is mixed driving 40% city 60% highway


only modifications are 275/85/16 tires

just did a tune up on the truck new wires cap rotor plugs, all fluids changed oil,trans, front and rear diff



can anyone help me figure out how to get better mpg

thanks
zach

 

Now that it's summer air up your tires more, and check your front 02 sensor.

 

look right up on top of tis forum at the first sticky and see if it sound like you issue

 

dosent sound like whats going on,

i checked the o2 sensor with a scanner and i can see the valuse switching back and forth

 

Still have the stock 3.55 gears with those 34.5 inch tall tires? That would be one of the primary reasons you get crappy gas mileage.

 

these are what you can do and you will see an improvement


-Re-do your exhaust (CAT especially)
-02 sensors
-Timing Chain
-Plenum gasket
-Electric fan
-Do something about your gears, if you have 3.55's with those tires, it will suck gas, and be harsh on your transmission

 

truck only has 75k miles

 

With a 2500 wouldn't he have 4.10s? You also have to account for the larger tires covering more ground.

 

standard gears were 3.55's. (that's what mine has.....) 4.10's were an option.

 

Sorry, didn't know it was optional. My 01 2500 came with 4.10. Just thought dodge was smart enough to put the lower gears in a heavy duty.