Terrible Mileage--help me if you can

[Michael Fowler]

After reading a Matthias' wonderful fuel mileage, I ran a check on my '94 F250 4X4 extended cab.
Mine is closer to 15 than to 30 miles per gallon--running basically empty at speeds under 62 mph.
It has oversized tires LT 265/75/R16.
It might be lifted a little.
The timing has been set by Mel. ( We need decals--" Timing by Mel")

I know the 4X4, over sized tires, and some lift all work against good fuel economy. Is 15 mpg the best I can hope for?
How can I tell if its been lifted--I don't have a stock truck to compare. There does appear to be a spacer under the rear spring, but it has what looks like a little handle sticking out to the inside of the truck. There are pads, maybe 1/2" to 3/4" thick under the front springs.

 

[Dsl_Dog_Treat]

Michael,

IIRC the stock 250 rear blocks are either 2" or 4" and yes they have that goofy frying pan handle end. The fronts sound stock from what you're describing.
The tire size will slightly alter your mileage but not record breaking by any means.
What gears are in it?

Have ya hauled a load with it yet to see what type of mileage numbers yer throwing down?
It seems some of em get better hauling a load and some get worse.

I know for me I get better mileage hauling than empty but me thinks I got my skillz from Travies goat boy school of driving.

 

[Sycostang67]

You get about what I do. I was getting about 16mpg when I got my truck stock. I added all my extra parts, toolbox, bigger wheels/tires, turned up pump, etc and it didn't change my mileage at all. I filled up the other night and was close to 17. It seems 15-20 is fairly normal for these trucks.

 

[dyoung14]

My white truck that i just sold would get 21 mpg with 285/75/16 tires on it even with my pump turned up

 

[ameristar1]

For what you have, you're not doing too bad. I guess if you want the big mpg, you'd have to go tall on the gears and keep the rpm down to 1600-1800 rpms, lower the truck, skinny tires, improve the aerodynamics somehow (cap, bed cover), synthetics front to back. Cam swap, maybe?

 

[GRU]

im getting 16 empty (back country roads, little town driving) and 10.5 - 11.5 towing a 24 ft 5000 lb ( + or -) coachman at 60 mph. 265/75, 5 sp and 4:10s. pumps turned up, timing not checked yet. oh, and thats running a 50/50 WVO mix.

 

[david85]

Keep in mind the nightmoose is also a featherweight compared to others here. Barely over 3000lbs empty. Thats just not possible with a 6000lb+ 3/4 ton 4x4 with probably close to 30% more frontal cross section.

I will never use anything other than the stock 235/85/16 tires on my truck for this reason alone (they also cut through standing water rather well in the rain).

Not only does the tire profile matter, but so does the tread. I am running highway ribbed tires that have relatively low rolling resistance. Some aggressive all terrain tires will help off road and look cool, but there is a price to pay moving the truck down the road.

Some things you can check are:

1 fan is not stuck on after warmed up

2 thermostat is not opening too soon

3 Tire pressure (sorry, but I had to mention it). Run a minimum of 70 PSI on all 4 corners if you have the correct 80 PSI load range E tires.

4 Do you have a high rise canopy or sun visor installed? those are basically big air brakes.

 

[Goofyexponent]

I have a stock height 1993 F250 4x4 with 265/75R16's on it and I can average between 18 and 20 MPG out of it easily. Last week I picked up a motor (spare 7.3 IDI) and drove 150 kilometers with it along with 500 pounds of extra crap in there and I still got 17 MPG with 1500 pounds in the truck.

As far as I know it's totally stock, I turned the pump up 1.5 flats. It is automatic, has 3.54's

 

[Compu Doc]

After reading a Matthias' wonderful fuel mileage, I ran a check on my '94 F250 4X4 extended cab.
Mine is closer to 15 than to 30 miles per gallon--running basically empty at speeds under 62 mph.

I'm getting 15.5 running 55-60. Truck weighs 10,000 empty but it has a lot of stuff in the back so I don't know what the weight is. Gears are 4.10 running 215-85x16 E4OD. So I guess mine is pretty good.

 

[Shadetreemechanic]

After reading a Matthias' wonderful fuel mileage, I ran a check on my '94 F250 4X4 extended cab.
Mine is closer to 15 than to 30 miles per gallon--running basically empty at speeds under 62 mph.
It has oversized tires LT 265/75/R16.
It might be lifted a little.
The timing has been set by Mel. ( We need decals--" Timing by Mel")

I know the 4X4, over sized tires, and some lift all work against good fuel economy. Is 15 mpg the best I can hope for?
How can I tell if its been lifted--I don't have a stock truck to compare. There does appear to be a spacer under the rear spring, but it has what looks like a little handle sticking out to the inside of the truck. There are pads, maybe 1/2" to 3/4" thick under the front springs.

What axle ratio do you have, and what transmission? My 94 turbo 4x4 running 265/75s would consistantly deliver 22 on the highway and 18 empty around town, but it had the EOD auto and 3.55 gears.
I currently have a 94 turbo 4x4 with 285/75s and all I can manage out of it on the highway is 18. It also has 3.55s with a zf-5.
I think the most important factors are
1. How you drive
2. Axle ratio
3. Tires
4. injection system condition.
My current 94 smokes under load no matter what the timing is, so I am thinking the injectors are killing my mileage.

 

[Russ]

Michael, I think you about right with this new garbage we have to use for fuel. I used to pull down 16 with my truck going back and forth the work, now the best I can do is about 13.

 

[argve]

Michael,

You're doing good with the set up you have, as said Little Agne has a very light truck compared to most diesels so he's gonna sip fuel that's for sure.

 

[crashnzuk]

I wouldn't call 15 terrible, I'd call it very average. Single digits would be terrible. Also, I wouldn't really call 265/75 "oversize" since they are only slightly wider and they are within a hair of the diameter of a 235/85. Everyone claims 20+ mpg on any diesel no matter the load or geography traveled when talking on the interweb. My Dodge gets 16-17ish during usual driving about town, and usually 13 when towing. My truck is appearently the lone 1st gen dodge getting less than 21 on the web
Travis..

 

[Diesel JD]

Yeah the Dodge guys always claim big #s and to some extent I believe it. Mine has gotten between 11-15 in town and 15-17 empty on the highway. If I could get 15 in town and 20 on the highway I would be ecstatic. I've advanced the timing and replaced my bad injectors we'll see what that does.....

 

[LCAM-01XA]

Travis is correct, 265/75-16s are only an inch wider than the factory 235/85-16s, and not any taller, so I'd imagine their effect on fuel economy is pretty small. I certainly didn't notice any drop in fuel economy since I installed a pair of those n the front of my truck, it was getting solid 19-20mpg on long (several hundred miles at a time) freeway trips, and that's what she gets now too. I do drive at 57mph (1900 rpms) all the time tho, I guess this speed is low enough where non-aerodynamic things like my Lund visor, high-rise bed cap, and the fullsize spare wheel sitting across the truck in front of the grille don't matter much either... Now in-town it's solid 12-13, no matter how I drive it, stop and go just brutally kills this thing. I'd say check if your rear brakes are dragging, as that would hurt fuel economy big time. Pump tires up till they're near max pressure, 70spi is a good setting. Make sure hubs are unlocked, if you have the automatic ones they sometimes get stuck locked so even tho your transfer case is in 2wd the front driveline is still turning and that increases drag too...