A few weeks ago I bought a stock grail truck and drove it from Montana to Michigan and averaged 21.36 MPG on the trip home (unloaded with a topper.) Needless to say, I was happy.

I just did the same drive in reverse, but this time pulling a small, flatbed aluminum snowmobile trailer with one sled and a dirtbike on it (combined weight of around 2,000 lbs.) I also had about 700 lbs of tools and gear under my topper. This time my tanks ranged from 14.6 to 16.4 mpg, with most being right around 15 MPG.

I was driving the same both ways, cruising mostly under 65 mph and 1800 rpms. Is this enough weight to drag my mileage down that far?

 

Whats the elevation change both directions? One way uphill? That does eem like too big of drop from such a small load. I have gotten as high as 17 towing my Jeep on a flatbed, and I have an automatic.

 

head and tail wind will also change things along with elevation

 

I thought about elevation, but my worst mileage was actually coming through Minnesota and North Dakota, and the tank where I climed 3,000 ft (GPS verified) in Montana was one of my better tanks at 16 mpg.

The only thing I've done to the truck since my drive home when I bought it was change the fluids, tab the KDP, and put on a new serpentine belt. I even switched from 245/75/16 no-names to 235/85/16 Toyo AT's to try to improve my mileage (and yes, I accounted for the 5% increase in tire circumfrence in my calculations.)

 

I-90 right?
I've done the same round trip several times and always get worse mileage going west.
Once you cross the Mississippi it's all uphill plus the wind tends to blow from the west.
My best mileage ever was one tank with fuel to spare of 27.6 mpg going east on I-90 from Billings to St. Paul strong tailwind.

 

The wind resistance of trailer probablly accounted for lost milage more than weight. JMHO

 

"I just did the same drive in reverse"

I'd try a forward gear might make all the difference

 

What wind resistance ????????????? He was using a small flatbed trailer behind a truck with a cap everything should have been no higher than the tailgate.
If it had been an enclosed trailer then yes that would provide a substantial drag.

Must have been the up hill combined with the wind and the little taller tire giving you a little taller axle ratio. Did you get a tank of poor quality fuel ??
Much lower milage from it compared to the others ??
Another thought perhaps your fuel filter is getting plugged has your mpg returned back to normal now ???
Still seems like a very big drop i only drop from 21.3 down to 17 pulling my 5th wheel camper here on mostly flat ground running 64 mph now that thing has a little wind drag Jayco 305 eagle with a slide out weighs 8500 loaded.

 

I'm headed down to Jackson Hole tonight so I'll report back, but I should probably change the fuel filter either way. At Napa they sold me a cartridge type (with the pleats visible from the outside.) Is this the right one? What's the best way to change it?

Also, I did a search and didn't find much on shop manuals. What's the favorite around here.

Thanks for the help fellas

 

Yes it sounds like the correct filter it is a drop in element and that one should fit 97-99. Just make sure you don't get any dirt in the canister while installing it and be sure to either fill it manually with clean fuel or with the lift pump before you try to start the truck. If you are concerned about spilling fuel and making a mess when removing the old one you can put a large ziplock bag around it during the removal process.

 

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