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Discussion Starter #1
I recently purchased a 1996 F350 4X4 dually with a low mileage 7.3L in it (57,000 miles) and an 8' X 11' steel flatdeck on it. The engine is solid, leak free and runs like a champ. Although I was expecting the 7.3L to be thirsty, I didn't expect it to be like a drunken sailor on shore leave. Are there any tips or relatively easy, tried and true modifications that folks do to improve their mileage on these engines? I eventually plan to put a camper and storage boxes on the flatdeck so it will be carrying some modest weight, but its got an 11,000 lbs GVWR (8,250 GVWR just for the rear axle) and I drive it pretty gently so it won't be stressed.

Thanks.
 

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What do you consider bad fuel milage?

Are you figuring it by hand or by the tank level?

I'd wager that it has 4:10's in the rear end which are not good for mileage but you should get around 15mpg here in the winter

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Discussion Starter #3 (Edited)
What do you consider bad fuel milage?

Are you figuring it by hand or by the tank level?

I'd wager that it has 4:10's in the rear end which are not good for mileage but you should get around 15mpg here in the winter

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I haven't done any calculations yet re: fuel mileage, but will start tracking with some care starting next fill up.

I did neglect to mention the gearing...I don't know what it's got or how I could easily find out, but it's rather low and I find that I'm shifting into 4th and 5th relatively quickly and cruising at 55 mph or so roughly 1700-1800 rpm.

Re: expectations, I'm a bit spoiled I guess as my daily driver here on Vancouver Island is a VW Golf TDI that gets about 40 mpg. I was hoping for 15-20 mpg from the 7.3L as most of my driving is highway back and forth between Nanaimo and Victoria, but suspect that's overly optimistic.
 

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It does sound like you have 4:10's in the rear.

The fuel gauges in these trucks are notorious for being off some. In my truck you can go 100 miles + once the rear tank hits the E but it drops like a rock from full. The front tank is the direct opposite, it'll go forever on full but you better have diesel in the rear once it hits the E

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Discussion Starter #5
Thanks Bugman.

I just checked the door sticker and it has the F5 axle code which appears to mean the 4:10 rear axle ratio. Certainly great for pulling...highway cruising not so much.
 

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Except for the mileage I'll run my truck with 4:10's all day long at 75-80mph on the freeways

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My 94 DRW in my sig basically got around 16 mpg with the 5-speed and 4.10's (no 4x4 though). Try to keep the rpms down around 2k for better mileage on the highway. Mine would turn about 2550 rpm at 70 mph. Cheers!
 

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Ford published several TSBs about it, and most of them are on this page:

(click this text)
 
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I haven't checked my fuel economy lately. I know that it can get 20 mpg (hand calculated) if I keep it at 2000 RPM in 5th gear. But 58 mph takes discipline that I usually don't have!
 
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Check out Fuelly.com to get real world estimates on fuel economy.

1. Driving Style.
2. Tire size and tread design.
3. Synthetic lubricants if operating in Cold Temps.
4. Tunes/Programs.
5. Lift kits.

If you can post your KMs and Liters, I think BoboftheNorth can convert it into the proper Lingo of MPG 😀
 
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Best I ever got was 18.9 hwy hand calculated.
 
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Check out Fuelly.com to get real world estimates on fuel economy.

1. Driving Style.
2. Tire size and tread design.
3. Synthetic lubricants if operating in Cold Temps.
4. Tunes/Programs.
5. Lift kits.

If you can post your KMs and Liters, I think BoboftheNorth can convert it into the proper Lingo of MPG 😀
158995

1613101772546.png


About sums it up...
Those that get much better than average have flat terrain and very few stops or traffic on their normal routes. No tricks to setting these trucks up but you need to make sure all sensors are working properly and for those folks facing colder than normal winter temps - using the engine/coolant heater is required to help get the engine up to normal/efficient operating temp.
 

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Discussion Starter #15
View attachment 158995
View attachment 158995

About sums it up...
Those that get much better than average have flat terrain and very few stops or traffic on their normal routes. No tricks to setting these trucks up but you need to make sure all sensors are working properly and for those folks facing colder than normal winter temps - using the engine/coolant heater is required to help get the engine up to normal/efficient operating temp.
Great information Craig. Thanks for that.
 

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Discussion Starter #16
Just a short follow-up...have run through a few rear tanks of combined highway and city driving, including some heavy snow and am averaging 13.5 MPG (US gals). Seems about "normal". Thanks for all the responses.
 

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Yes, you are doing pretty good at 13.5 mpg. The average is around 12.
 
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