This was my first real run on the highway since I bought the truck a few months ago. I knew it wasnt getting the best mileage to start, but here is what happened.

I purchased an RV and went to pick it up 250 miles away. My trip there empty, non stop on the interstate got me 15.5 calculated MPG. Not the best, but at least I figured I could work with it and try and improve it.

Once I hooked up the the 9000lb 32' 5th wheel, my mileage dropped to 8 MPG!! I tested it first at 60mph and about 1700 rpm for the first 77 miles. I used 9.5 gallons of fuel. I refilled, and in the remainder of my trip I used 18 gallons in 150 miles at 65-68 MPH and 1900-2000 rpm. Not much of an improvement.

So, do I have a problem? I expected it to pull better once it was worked. I always expected only a slight drop in economy whether a diesel was loaded and working or not.

I also have an 03 GMC HD1500 crew with a 6.0 gas. On the highway empty it gets 16MPG, but I dont think the mileage drops off like that when I hook upto my previous RV (30' and 6500 lbs).(10-11MPG?) I definately like the steady pull and hp better with a diesel, but 8mpg wont get the family out camping much!

Basically, the truck is a stock 2002 F250 Crew 7.3/AT with a 6637 filter. It has 133,000 miles on it. The truck runs smooth and doesnt skip a beat!

I hate to start another mileage thread, but what are other getting pulling similar loads? I live in the prairies, I only have a few small overpasses to climb! Are all these 5th wheel pullers only getting 8MPG??

Thanks

 

Don't feel to bad, i,m with yaa. I got a 31 foot TT at 7,400 loaded and get about 9 maybe 10 on a flat run with a real easy foot. 7 or 8 up and down hills around here. I,m estimating.

 

Sounds a little low to me. I just pulled 7 tons of hay on a trailer that weighed 3K and got 10.5 mpg. I ran between 55-60 mph and had a couple of 6% pulls of about 1/2 mile each. Also with my 31' TT I have been getting between 11-12. This is all hand calculated.

 

Mine burns approx 10 liters an hour, 12 pulling 30 ft camper.

More, or less depending on wind or terrain.

 

That sounds low, you should do a little better unloaded. I just had a trip not to long ago to pick up a car in nothern california and back down to orange county. The trip was a little over 500 miles at about 5500 lbs and I got a little over 16mpg. I thought it was pretty good, I get over 20mpg on my daily duties without a load but a lot of traffic stop and go, which I know diesels don't like if your looking for fuel economy. Oh and I was driving about 70 most of the way and a little faster when I had the oportunity.

 

It may have been some ultra-low sulfur diesel that you filled up with. My truck HATES that stuff! I normally average no less than 17-18mpg with low sulfur diesel; with ultra-low 15 mpg, 16 IF I'm lucky and the truck is in a good mood.

 

My best is a little less than 19. That's keeping at 65 or less and no jack-rabbit starts. You should definitely be better than 15-16 -- I get that hammering it regularly. This is on a 2WD truck on stock tires and 3.73 gears.

Another issue is that without the Harpoon mod, it's hard to get a good sample unless you wait the 10 minutes it takes to get those last few gallons in filling it to the neck every time. That could be throwing off your math as well.

 

Yea, that will differently through off the calculations a bit. I can stand there fartin around with filling it up for 1/2 hour if i wanted to. I know i can squeeze in more than a gallon or two. Which could be, at least, 40 mile difference.

How far off is your speedo, Are you really doing 75? I think something is wrong. Those are some really know numbers for highway. My numbers crash after 70mph.
I run (best guess without the harpoon mod performed, YET ) Thruway driving 65mph i run 20-24 mpg Empty.. Thruway driving with 10klbs 5th wheel 65mph.10-14.

Have you ran through the normal maintenance items? EBP sensor/tube. Bearings, Bearings on trailer, Brakes any brakes dragging, Tires PSI, Etc. The normal MPG gain items.

 

About what I get.. Just wait untill you get in the Mt. Try to keep it under 70 mph for sure .. That is why we did not pull this summer ;; with the price of fuel..

 

Threads like this seriously get me rethinking my plan of a camping trailer, any long trip and it becomes cheaper to stay in a hotel now days (though not as fun for sure)

I figure i'll go all out, 30' trailer with 25' boat behind it! If I am gonna drink diesel, gotta do it right!

 

Is your new trailer one of those tall ones with the large front?
The wind resistance will really kill the mileage.
I get 8 if I insist on going 70 and 9.5 if I go 65.
4.88 axle. 2500 rpm at 70.

 

How much does one of those wind divertors help, sorry, dont really know the name of it..I am refering the adjustable fin I see on a lot of trucks pulling fith wheels.

 

Ernesteaugen had one, I think.
I don't know the answer to that question, but would like to know.

 

That sounds low, I pull a 48 ft L/Q race car trailer at a gross weight of 26500 lbs and I get 13.0 to 14.5 mpg, unless like Kwikkordead says you are pulling a brick wall behind you. Then you might want to get a wing that goes on the cab, and a open tail gate, it would save you money in the long run.

 

Also, I would want them to be easily removed once arrived at the destination.
I think they make an empty truck look like a tricerotops.