while i've only run 3-4 tankfuls thru the new addition (2001.5 H.O. 6 spd 3.55 gear 3500 4x4 dually...67,000 miles ) very stock seem to be holding right at 15-16 mpg mixed but conservative (ie light foot) just recently did synthetic front and rear axles and was wondering if fuel filter change can sometimes pop up the mileage...next stop is the dealer for lift pump check ...from what i have been reading that can sometimes be a source of poor mileage...any other thoughts ???? thanks ..my son and I really enjoy reading your notes so keep up the good work and remember our guys overseas<br>

 

Just had the lift pump replaced on mine at 50, 000 miles,found it wasn't working at all. after doing a filter change the truck would not start, i just bought it so it may have been cooked for quite a while, but i was getting good mileage (21.mpg can. highway) and started great even in very cold weather, no sign the pump was gone at all. Diesel mechanic told me that loss of power might be the only tell tale sign, but i didn't notice that either. With the new pump on it runs just the same as it did with the old one.<br><br> rob

 

If your running 73+ on the open road, thats what your're going to get. My best fuel mileage is just a needle under 70. <br>18.5-20mpg. Ran from Wilmington NC to Scanton Pa on one tank in Sept of 2001. That was my best ever. Had some good fuel in there also. My 96 CTD will run from New Orleans to Melbourne, Fl without stoppin at 70mph. (3/4 ton long box extended cab, 3:55) Towing is the same, the faster you go the lower the number. Don't seem to matter what your pullin. <br><br>Dave

 

I have the same truck and miles, I get the same as you, I get a couple better on summer fuel. With 4.1 gears, my mileage does suffer above 2100 or so.

 

Keep in mind, &quot;winterized&quot; fuel sux for mileage and performance. Expect better in the spring.<br>

 

With 4.10's, that is probably near the best it is going to get. I have 3.54's and get 18 to 20 and a fudge more if I stay off the go fast and loud pedal but we all know that's no fun.

 

I'm running 4:10s, and find that if I set the cruise to 2000 rpm (about 60mph), my milage improves. Still not astronomical, but above that, it falls off as speed increases.
Remember, we are driving a diesel powered brick.
Our aerodynamics suck.

 

I have pretty much the same question I have a 01 3500 with 4:1 4speed auto also has about 72thousand . I just took a 1000 mile trip and got about 14mpg dragging about 10,000lb. Is about the nom,We did run right around 2 to 22 hundred rpm's. trucks al stock no mod. yet.but coming. ???

 

You done good. especially dragging weight.

 

Oh, Shovel don't say that I was hoping that I could do better. Oh well I guess I see a 150 gal. fuel tank under my tool box ah. :'(

 

??? 14MPG dragging 10K ain't too shabby.<br>What kind of milage were you looking for?

 

Well this is my first dodge and I love the power and what more it's about adicting I was wondering if a box and opening up the pipes. Would help. What kind of mileage do you get.

 

my dually gets around 16 to 17 the other dually i had got the same. what do you want for a daully 4x4. 17 is usaully what you can get with a 1 ton 4x4 dually. i would get the lift pump checked tho since youre around the right mileage for it to die

 

Zoomie, BOMB your truck and you will get better mileage. Fueling box that also adjusts timing (suggest a Comp box or equivalent and leave the pump wire dangle for now) should gain you 1 to 2 MPG increase unless your right foot grows heavier with your new found power.<br><br>Roger

 

Best I ever got with 3:55 rear was 21 mpg. That was keeping it below 75.<br>Just went Tulsa to Atlanta and back last week. Got 18.5 to 20 mpg while running 75 to 78 mph.<br>I even get 18 around town.