7.3L Fuel economy

[powerstroker]

Hello all,
Recently purchased a 2001 F250 Super Duty with the 7.3L Diesel- WOW what a powerhouse!!! It's 2WD and automatic, 4 door long bed. What kind of fuel mileage could I expect not pulling anything on the highway? I figure I'm getting 16 mpg driving @ 75 MPH. If I drive 65 I get about 17.5 MPG. There are no mods to the engine other than a K&N air filter. I have installed an Edge evolution programer for info purposes to see what temps I'm running, boost etc.
I have it on the stock setting. I have a friend with the exact engine, 4 dr short bed and he gets 14 mpg pulling a 10k# 5th wheel, and 19 empty, is that possible or just another case of you should have seen the fish that got away.

[Herb]

Congrads on your purchase. To me that mileage seems to be around normal for a 7.3 PSD. My cuz has the same truck but a F350 he claims over in mid 20's on highway empty. I could never get more than 21 mpg highway on my Dodge CTD empty.

Light foot will help increase your mileage. Synthetic oil you should be able to increase some MPG, also a air intake system to help the PSD get some good air.

[johns4dor]

Hey Powerstroker,
'01 is a good truck. A bud of mine had a 2wd 250 supercab, stock w/air filter replacement like yours. He was getting 17-19 mpg @ 70-80mph. He took out the K&N and replaced it with an AMSOIL "dry" filter to get rid of the oiled filter and to stop more dirt. K&N's flow lots of air but don't stop the dirt like they should. I have a 2002 crew-cab 4wd 350. In stock form it got about 15 on the open highway, but it would drop off over 60mph. I made a few power changes as you can see in my signature. Mileage went up to over 20 on the highway when empty and it does it best when @ 68-72mph, even when towing my 10,000 lb. trailer. Took a long trip a couple of years ago and averaged about 14 until I came back into Oregon and Calif and had to slow it down to 55-60. Lost 2 mpg at the lower speed. You already have the "Edge", but be sure to change the intake system and exhaust before you start using the upper settings. More air in, more air out. They are almost mandatory to keep from hurting things when you are making more HP and help to keep the EGT's down.

[Errick Bodenheimer]

Hey powerstroker if you can find someone with a IDS you can go in to fuel economy and get a close reading!!!

[mexicoF250]

I've had my f250 (pre-1999, 7.3L) for about 5 months now . . . And I'm getting only about 13.7-14.0 mpg. Granted I drive around the city for the most part . . . but it doesn't seem to matter whether I'm heavy on the pedal, light on the pedal . . . I could pretty much go to vegas and gamble on how likely the mileage will be between 13.7 and 14.0.

So, is this normal, from what I've read, seems something is wrong?? I put on a 4 inch straight pipe(which should be better mileage) . . . I've got 305-75 load range E tires, inflated around 54psi or so. I put in an aftermarket filter, it is not K&N, but it is an equivalent setup that is nicer I think. S&N might be the manufacturer?? I have the superchips tuner, but right now the truck is NOT TUNED . . .

Does anyone think I should tune the truck and see what difference it makes?


Oh yeah, I've had a HPOP leak for the last 3 months. Finally decided to try and fix it myself. I did that yesterday . . . still leaking today, but not as much . . . I'm thinking some oil is still left on top of the engine that is still dripping down looking like a rear seal. Could the HPOP have any affect on the mileage?


Thoughts, ideas and opinions would be greatly appreciated. Thanks.

[johns4dor]

Your mileage is actually pretty normal. Yes, tune it. You will feel the power. Don't expect too much change around town, not more than 1 or 2 MPG. The big change will come on the highway. 2wd will get more MPG than 4wd. You also need to make sure your speedo is accurate with the change to big tires. The big tires may also cause a drop in mileage around town and when towing.

[mexicoF250]

Thanks for the thoughts. It is 4wd, but for some reason, I thought 4wd only was worse when driving IN 4wd . . . I guess the extra moving parts/weight would build up resistance that can be seen in the mpg.

Speedo I imagine has to be off . . . what is stock on that truck, 265-75?

But, I've tried to do the math(my degree) and it seems that I'd probably only have an error of maybe 1 mile every couple hundred. I figured it out a while back, don't remember, but I do remember it wasn't very significant. I figure speedo calculation error could make the mpg come up 0.2-0.3 at the most.


You think tune it. Ok. I have the tuner, but I've been scared to because of all the talk I read about with exhaust temps and such. I know I have the right exhaust to tune it. (4 inch down pipe all the way to the 5inch tail pipe)
And I have a great air filter. And to boot all that, I have the exhaust temp gauge and the turbo boost gauge . . . just haven't installed them because I don't know how and I don't trust the local Mexican repair shops to know how on my diesel.

So, do you think it is safe to tune it and run it conservatively without my gauges being installed yet? And, do you think I can install the gauges myself without trouble?

Thanks a bunch.

[mexicoF250]

Oh yeah, anyone think putting synthetics in my pumpkins and in the transmission case will change my mpg significantly?

And . . . I know I should have a signature with info in it. Where do I put my signature? I have looked high and low and can't seem to find anything related to editing it.

[johns4dor]

Hi Mexico, Yes, the 4wd extra weight and drag of the front end does cause a loss even when not in 4wd. Stock tire size is 265 x 75 x 16. I put on 285's and my speedo is dead on according to the GPS. If you have the directions with your gauges and some mechanical ability, you should be able to put the gauges in without much difficulty. You probably won't overboost, but the EGT is critical if you are towing. Under normal empty truck driving conditions you shouldn't have any EGT issues. Be sure to mount the EGT sending unit on the lower side of the curve in the left exhaust manifold so you have the before turbo temps and try to keep them below 1200 most of the time. Bursts up to 1400 for short periods won't normally cause a problem. Answer to the last question: yes, put synthetic in the trans and diffs, engine too, preferrably AMSOIL, they are the best. No. you probably won't notice a readable MPG difference, maybe a little, but you will get a lot more protection, and using AMSOIL will get you a lot more mileage between changes. Good luck.

[2002BigRed]

I've had my f250 (pre-1999, 7.3L) for about 5 months now . . . And I'm getting only about 13.7-14.0 mpg. Granted I drive around the city for the most part . . . but it doesn't seem to matter whether I'm heavy on the pedal, light on the pedal . . . I could pretty much go to vegas and gamble on how likely the mileage will be between 13.7 and 14.0.

So, is this normal, from what I've read, seems something is wrong?? I put on a 4 inch straight pipe(which should be better mileage) . . . I've got 305-75 load range E tires, inflated around 54psi or so. I put in an aftermarket filter, it is not K&N, but it is an equivalent setup that is nicer I think. S&N might be the manufacturer?? I have the superchips tuner, but right now the truck is NOT TUNED . . .

Does anyone think I should tune the truck and see what difference it makes?


Oh yeah, I've had a HPOP leak for the last 3 months. Finally decided to try and fix it myself. I did that yesterday . . . still leaking today, but not as much . . . I'm thinking some oil is still left on top of the engine that is still dripping down looking like a rear seal. Could the HPOP have any affect on the mileage?


Thoughts, ideas and opinions would be greatly appreciated. Thanks.

Well at 142,000 miles my HPOP died, I finally had it replaced. Truck never ran so good at that.
Not cheap to replace but work it.