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How to get better fuel economy w/your diesel



  • It's seems like it's been forever that I wanted a Dodge Ram 2500 quad cab and this tuesday 9/19 it happen got an 06 Big Horn 4x2 auto trans and limited slip. I'm 54 years old all I can say is WOW everything I hoped it would be. Avondale dodge fleet dept. ROCKS they drove it up from tucson for me and it even came full of fuel. Only the odometer LCD does not work. My girlfriends cousin steve wanted me to get a DuraMAX and her other cousin Victor has a powerstroke. But I think cummins is the best.
    I have been reading comments from all you guys for at least 8 years about your diesels. Well welcome me to the club. I'm ready for some advice. By the way I named her " Lucille" after lucille ball
  • Silly me ,I took the word of a 20 something [ he drives a 05 Ram 1500] who said it was under the tach. When actually it's under the speedo. Yes my odometer does work.
  • cdb3cdb3 Posts: 1

    I will share with you what I have learned about mileage on the truck you mentioned. I have driven a 2001 F250 with the 7.3 P-stroke for 4 1/2 years.

    You cannot go by the mpg readout for the short term. It can be fun to play with and may be used as a guide but it is not accurate. Certainly don't trust it to accurately tell you how much further you can go without fueling! You can reset it by pushing both buttons at once while in the mileage mode. Did you know it measures temperature and distance to empty as well as mileage? Toggle to the different modes by pushing the button on the left side. It can also be set to measure in metric.

    The only way to get an accurate reading for your mileage is by carefully filling the fuel tank all the way to the top of the filler neck until fuel no longer runs down. Pumping diesel is not unlike pouring warm beer - lots of foam. Ford has never chosen to put a large filler hose on the pick-up tanks like I think Dodge does. Completely filling in warm weather will take about five minutes after the filler starts to automatically shut off.

    Anyway fill it up into the filler neck until fuel is w/i 1/2 inch of the cap and stays there. Drive until you have used up 3/4 or more of your fuel. Fill up the same way. All the way to the top, get past the foam! Use a calculator or pencil (God forbid!) and divide the gallons into the miles.

    Do this for every kind of trip for a year and you can see what your truck is really doing.

    These trucks do much better on the highway than in town. They will run like hell but if you want better mileage accelerate slowly, use cruise control and keep your speed down. Wind resistance at 70 mph is twice as much as at 55 mph (as per NPR last week.)

  • santa1santa1 Posts: 1
    Last January I bought a very nice used 01 F-250 7.3 Turbo prw stroke.It is a 4dr shortbed ( my wife and I,75 & 70,enjoy the comfort), I am a professional Santa Claus and we travel to SE Pa. every year to do Santa, my question is- can another fuel tank be installed in place of the spare tire? We have a 30 gal single tank and would like to have an aux. to take advantage of the (rare) times we find a good deal on Diesel fuel. I haven't been able to find any info on doing this here in South Central Texas. Does anyone have answers for the "Old Folks"? Thanks, Santa
  • I purchased my F250 4X4 crew cab diesel in Feb. 05 at that time diesel was about .10 cheaper than regular gas. Today the price of diesel is 0.75 more per gallon than regular! Does any one know why diesel is more now and should this trend continue?
  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,495

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • My '02 7.3L consistently gets 15 to 18 mpg, loaded empty, combined gross vehicle weight of almost 30,000 lbs (over the rating, DO NOT try pulling that kind of weight without airbag suspension and equalizer hitch and bars). I can be pulling passes or running flatland. I have the superchip and K&N million mile air filter, otherwise bone stock motor. Keep your tire pressure up, it changes with temp and altitude. Top speed is 95 mph, not built for speed, built to PULL. Nothing really seems to vary my average or tank to tank mileage.
  • Guys,
    Here is what I have learned over the past 4 years or so with some experimentation.

    First off, let me say, my stock 2002 Ford 7.3 got about 15-18 mpg. I drive 140 miles round trip (all interstate) to work and back so I have had plenty of time to figure out what makes it tick.

    Gearing is everything. My truck runs 3.73 rear ends. To the engine I have added a K&N filter and air box. I also modified the front intake behind the grille for better airflow. The stock intake was about the size of a silver dollar and I took a dremel and opened it up. Also, a 4" exhaust made a big difference. The engine had more "snap" and it lets the turbo spool up noticibly quicker. I also have reflashed the computer with a power programmer. I left it at the 60 HP "performance economy" mode. I am not drag racing it and I was going more for mileage. I also reprogrammed the transmission for stouter shifts. As you all know, the stock transmission setting is a little mushy. Also, a set of decent quality gauges are an absolute must. Heres why: The lower you are able to run the boost, the better your fuel economy. I have experimented with different highway speeds and found that with the 3:73's 55-60 MPH equals 24MPG. The faster you go the more boost the turbo produces the lower the fuel economy. At 70 MPH the mileage drops off to around 20MPG. Now, if the gearing were a little taller say 3:08 it would stand to reason that the fuel economy would be better at highway speeds. Conversly, with 4:10's or lower expect the turbo to be building more boost at highway speeds and fuel mileage to suffer.

    Food for thought.
  • ezshift5ezshift5 Posts: 852

    ".....I have experimented with different highway speeds and found that with the 3:73's 55-60 MPH equals 24MPG. The faster you go the more boost the turbo produces the lower the fuel economy......"

    ..IMHO, that is impressive fuel efficiency for a 7.3l TD...
    well done!!

    (this from the left coast: 1.6l non-turbo trucklet.......

    seasons best, ez....

  • Cactus 5
    I have a 05 Dodge 4*4 HO turbo diesel w/ 14k miles
    My first easy add on would be a K&N air filter
    worth every penny, aprox cost $60 and you can hear the diesel breath easier after instalation.
    After break in period I would highly reccomend full synthetic oil for the motor. The rear end should be synthetic already from the factory. Keeps it cooler and actualy reduces some noise!
    Hope this helps

  • In case you haven't found an auxiliary fuel tank yet. You can get some from Northern tools. I think they have about six to choose from. Once u get one u can run a fuel hose from the aux. tank through the filler neck to keep your main tank full. I've got a 91 gallon fuel tank toolbox combo and love it.
  • jyardjyard Posts: 1
    Has anybody experienced fuel problems like this with your 05 diesel? The dealership preformed afuel economy update to the truck and my trans serviced also .I dont know if any of this has to do with the problem,but please let me know. Thanks John Y
  • tomk2tomk2 Posts: 1
    I'm not sure of this, but I was told that a lot of it has to do with the military demand for diesel. Since most (if not all) military vehicles use diesel, and with 2 wars going on, the military is using more diesel than they would in a "normal" period. It's a simple supply and demand issue. :(
  • gagricegagrice San DiegoPosts: 28,681
    Welcome to the forum
    Your take is logical. I don't know if we are buying diesel from refiners in the Middle East or shipping it from home. Good question to ask. I think a lot of the high price is the refiners are re-configuring to produce ULSD that is mandated this year. Some are already selling it, others are in the conversion process. That and the 3 refineries in TX that went off line in Rita did not help. May just be a combination of problems.
  • I received a notice in the mail about the update you just had completed, it says I may not be able to register my vehicle if I don't go get this done. I knew if it had something to do with registration that it could affect my Ca we're always re-inventing the wheel...I get fair milage but I'm worried about this thing...The notice gives me 3 years to have the update. :mad:
  • yrbenderyrbender Posts: 25
    Trying to get better mileage on my F250 asked the dealer about the larger intake and getting a 4 inch pipe to help air flow. He said both would void manufacture warrany and wait till after warranty period is over. Had a friend with a chip blow an enginer at 5k mile has to pay 15k for new motor no warranty due to chip. Anyone have any info on the intake or bigger pipe
  • stdbobstdbob Posts: 14
    What is the difference between on and off road diesel fuel? Off road is much cheaper.
  • cctdicctdi Posts: 82
    On road diesel is for the vehicles on the roads; passenger cars, light trucks, heavy trucks, buses. The dirt trucks, diggers on the mine field, farming trctors, heating oil are using the off road diesel which is colored with pigment. There is no difference between these two, but you are not allowed to use the off road diesel for the car on regular driving.
  • whisky6whisky6 Posts: 7
    Hi, this reponse to fuel of diesels my son had a 1999 f-250
    ford and one day we were driving around and checking the
    fuel mileage on the on board computor and we coasting down a hill and watching fuel mileage on the computor and we stopped believing what it saying when it got up to 55mpg
    so those little gadgets in these truck are a little off,thank,s
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