7.3 Powerstroke (Fuel mileage)

[old racer]

We currently tow our 325 SRX fifth wheel with an '01 Ford F350 with the 7.3L. On a recent trip to S. Dakota and back, the fuel mileage was what I call unacceptable.
Currently chipped with a plug in module underneath the dash, (don't remember the brand), power was not an issue however, our fuel mileage just wasn't there. When we left home, our first two tank fulls were 12.2, an 10.8 respectively. Once we got into MN. and S. Dakota, we went all the way down to 4.8 mpg., with a few tanks averaging around 7. I realize the wind always seems to blow out there, but this seems a bit extreme.
We've been looking into the Bully dog programmers. Are any of you currently using one and if so, any real numbers regarding fuel economy certainly appreciated.

[hankaye]

old racer, Howdy;

How was the mileage with the wind at your back
on the return trip...?

hankaye

[rhagfo]

What is "normal" fuel mileage while towing?

What gears and stock or oversize tires?

[sagebel]

How old is the engine oil? My old truck (2000 F350 w/ 7.3) would always get lower mileage as more miles were put on the engine oil. This is fairly common with most 7.3s. Are you hand calculating the mileage or getting it from the overhead display? Is this your first tow with the chip? Sorry for all of the questions to your question, just trying to get some more info.

[azlee56]

our 2000 3/4 ton 7.3 gets 22 highway without towing and 12 while towing. Interesting about the oil and mileage.

[rhagfo]

Old Racer, stick or auto?
I get 12 mpg pulling our 11k# 5th wheel with our 2001 Cummins. Doing 60 in the Oregon Coast Range, NV4500 5 speed.

[old racer]

old racer, Howdy;

How was the mileage with the wind at your back
on the return trip...?

hankaye
Interesting you should ask......When we turned to come home the wind switched straight out of the east and we bucked it all the way!! LOL!!

[old racer]

Auto transmission. Stock tire size, dont remember the gear ratio. Calculate each tank full manually for accuracy. The chip has been in the truck since we bought it 3/4 years ago. Have done quite a bit of towing with it including our former fifth wheel which was about the same weight and height, and our 24' enclosed race trailer.
It never has done as well as my work vehicle which is an 04 duramax, but this is the lowest fuel mileage we have ever gotten. Really considering upgrading unless there is a programmer or?????? that will show some improvement.

[sagebel]

Has your mileage dropped when running empty?

[LittleJoe]

I'm sure you had a look at the air filter?

What speed were you trying to run.? Any more than 60 in a strong headwind is an exercise in futility as far as fuel mileage is concerned.

Do you have a EGT guage? and if so what was it running?

[old racer]

Fuel mileage hasnt really dropped when running empty. Gets about 14 /15 on average. Air, fuel and other filters are new, (less than 1,000 mi.).
Regarding speed, would like to tow around 60mph. Have tried with OD locked out, and the other way by just letting it do it's thing, dosen't really make much difference.

[sagebel]

I never locked out OD on my 7.3 unless it started hunting between 3rd and OD and it only did that with a headwind or on a grade. After re-reading your initial post, that is a severe drop in mileage. Have you noticed any other abnormal indications such as an abnormal noise, smoke, or oil consuption?

[Vidorcom]

It is what it is! I have a 2008 duramax..this past weekend towing west bound on i90 from moses lake to seattle...the head/side wind pulling my 30 fz number pull weighing in 11k gave me as low as 6mpg but by the time I made to Seattle 8.

You don't buy diesels for mileage while towing you buy for the power and low rpm's. I will not tow with a gasser!

[JRTJH]

Old Racer, The 7.3L diesel had some problems with porous cylinder heads and any air bubbles in the coolant caused corrosion and pitting. Ford recommended a "surfactant" called it a "cooling additive" to be added to the radiator coolant at regular intervals. If not added and if problems with corrosion developed, one of the problems seen was decreased fuel mileage. Of course there was also decreased performance, excessive exhaust soot, etc... But I would keep a close eye on the engine at this point. If your next tow produces the same mileage results, I'd start looking at more than just a "headwind problem"

[rhagfo]

It is what it is! I have a 2008 duramax..this past weekend towing west bound on i90 from moses lake to seattle...the head/side wind pulling my 30 fz number pull weighing in 11k gave me as low as 6mpg but by the time I made to Seattle 8.

You don't buy diesels for mileage while towing you buy for the power and low rpm's. I will not tow with a gasser!

I would disagree with that mileage statement.
I bought mine for power, longevity and mileage! I pull an 11.5K 5er with my 01 Cummins and see a consistent 11 to 12 mpg. Yes I loose mileage towing, going from 20 empty to about 12 towing, good luck doing that with a gas engine all day.
I am pulling that with a 3/4 ton, yes I know that 11k is back there on hills, but it doesn't run hot and I can maintain 55 through the Oregon Coast range.

[SmittysRV]

I pull with a 7.3 also and just got a new 5er that is much heavier than the last. I got 12.5mpg on the way to the river however on the way home I hit some gnarly head winds and got 8mpg. Can't do much about head winds, I just watch EGTs and slow a bit.

14531454

[Hansel]

My 2000 7.3L get around 16mpg around town, and when pulling my Laredo 284BH I get around 10mpg. But I've also found out that the harder I drive the worse the fuel mileage get's when towing. If I keep iy under 65mph I'm getting pretty good fuel mileage but if I run over 70mph is in the toilet:eek:

Was the truck blowing any black smoke??? That will be a sign of overfueling and will cause poor fuel mileage.

[antiqfreq]

We've been pulling our five 4 1/2 years now with a year being cross-country.

We usually get 12-13 MPG towing without a major headwind.

When crossing northern Texas towards Carlsbad, New Mexico, we had a headwind for about 6 hours and we got 7 MPG-argh-

We bought our 7.3 for the longevity of the motor and it is still going strong!

Jo

[Cool Canuck]

We currently tow our 325 SRX fifth wheel with an '01 Ford F350 with the 7.3L. On a recent trip to S. Dakota and back, the fuel mileage was what I call unacceptable.
Currently chipped with a plug in module underneath the dash, (don't remember the brand), power was not an issue however, our fuel mileage just wasn't there. When we left home, our first two tank fulls were 12.2, an 10.8 respectively. Once we got into MN. and S. Dakota, we went all the way down to 4.8 mpg., with a few tanks averaging around 7. I realize the wind always seems to blow out there, but this seems a bit extreme.
We've been looking into the Bully dog programmers. Are any of you currently using one and if so, any real numbers regarding fuel economy certainly appreciated.

I towed with a 7.3 for 7 years and never got down to 7 mpg. I would tow through South Dakota twice each year. :D I had a programer and had 50 mph headwinds (South Dakota) that tore the torque converter out of the truck without getting down to 7 mpg. :eek: A different programer is not going to solve your problem. If your numbers are correct, you need to find a mechanic that has experience with 7.3's. Check your oil level. If it is increasing, that would be a clue.