very bad mileage, new to the forum...

[Tylerspyler]

Well I finally decided to join this forum for help.
First my 03 7.3 f350 dually has been getting poor poor mileage since we can remember (like 9-10 mpg) The only thing we have gotten for it was a k&n drop in. Other than that it is bone stock. I know its a giant truck with a gint engine but what the heck, is it really suposed to get this bad of fuel econmy?

I have tried everthing from driving like a grandpa to driving like a tyeenage that just got his license. we also haul around a 14,000 lb goose neck horse trailer (the weird thing is the mileage stays the same, 9-10 mpg).

please, any help is appreciated.

[NoRalPh]

You'd be surprised how much it can cost you in fuel mileage with bad rolling resistance alone. Be sure your brakes aren't dragging, bad bearings, locked hubs, low tires... All this can add up to a significant addition in that rolling resistance and cost you.

Also, simple things like dirty filters, stuck EBPV, and anything that keeps your engine from running efficiently will cost you too.

That being said, 10mph on a non-towing dually IS low but, you might only be off by 3-5

Also, K&Ns Suck (literally) and will allow way too much dirt into your engine and turbo.... For the sake of longevity, there are better choices.

[Tylerspyler]

Originally Posted by NoRalPh

You'd be surprised how much it can cost you in fuel mileage with bad rolling resistance alone. Be sure your brakes aren't dragging, bad bearings, locked hubs, low tires... All this can add up to a significant addition in that rolling resistance and cost you.

Also, simple things like dirty filters, stuck EBPV, and anything that keeps your engine from running efficiently will cost you too.

That being said, 10mph on a non-towing dually IS low but, you might only be off by 3-5

Also, K&Ns Suck (literally) and will allow way too much dirt into your engine and turbo.... For the sake of longevity, there are better choices.

The only thing wrong with the tires and other rolling things, is one of the wheel bearings are going out, but that just started so thats not it. we own a tire repair shop so that stuff gets checked often.
I was reading about the EBPV. How would you determin if thats the culprit?

The meter is perfectly accurate (I tested it the hard way on fillups)

The k&n is not great, your right about that. try telling that to my father.

[KnockingDiesel]

I think the truck itself has a lot to do with it. I got my truck new at which 9.5 MPG was average, I drove at low RPMs with no load until 7500 mi. at which point I got 10.9 and now that I am at 65,000 mi I get 14.0. Duallies get pretty bad mileage in general, but it all depends on your set up, I have 4.10 gears, 235/85/16 tires, and a lead foot (I tried grandpa driving but got like .25 mpg more), I know a buddy that runs smaller tires and get worse mileage (higher rpm to maintain speed). I also calculate the mileage manually (miles driven divided by gallons of fuel used). The best I have seen on these trucks was 15 mpg on 2wd 3.73 truck. you can reset the mileage computer by pressing both buttons. just my 2 cents.

[Tylerspyler]

Originally Posted by KnockingDiesel

I think the truck itself has a lot to do with it. I got my truck new at which 9.5 MPG was average, I drove at low RPMs with no load until 7500 mi. at which point I got 10.9 and now that I am at 65,000 mi I get 14.0. Duallies get pretty bad mileage in general, but it all depends on your set up, I have 4.10 gears, 235/85/16 tires, and a lead foot (I tried grandpa driving but got like .25 mpg more), I know a buddy that runs smaller tires and get worse mileage (higher rpm to maintain speed). I also calculate the mileage manually (miles driven divided by gallons of fuel used). The best I have seen on these trucks was 15 mpg on 2wd 3.73 truck. you can reset the mileage computer by pressing both buttons. just my 2 cents.

Our truck has all the bells and whistles. It has the 4.10, its a lariat, 4 door, 4X4 sotf, two tone paint, dually, long bed, and to top it off its a 2003 with the 7.3. so I did not expect much. I did discover an odd thing, it actually gets 1.3 mpg better mileage if you are harder on the pedal then let off so it shifts earlier then get back on it for all the gears. I have gotten it up to 15 mpg but that was cruising on the hwy.

[KnockingDiesel]

Could it be a sensor that is screwing with the EBPV? I think they are temperature activated. My dad has a similar truck (2WD) and gets the same as I do. We are in Alb NM @ 5000ft elevation, his got bad mileage after a sensor or something went wrong coming back from a trip to LA Stealer said it was with altitude change, not sure how that statement was but they fixed it under warranty (Thank for FORD ESP) its good now. Sorry to be long winded but my point is it turned out to be a $25 sensor. Does the truck do anything out of the ordinary, does it act up every so often or anything like that?

[BIGBILL105 45]

My trucks milage seems to be down as well. I was getting getting right around 18mpg during the warmer months so maybe the ebpv is sticking.

[KnockingDiesel]

I know the winter blends can screw with the fuel economy.

[Tylerspyler]

Originally Posted by KnockingDiesel

Could it be a sensor that is screwing with the EBPV? I think they are temperature activated. My dad has a similar truck (2WD) and gets the same as I do. We are in Alb NM @ 5000ft elevation, his got bad mileage after a sensor or something went wrong coming back from a trip to LA Stealer said it was with altitude change, not sure how that statement was but they fixed it under warranty (Thank for FORD ESP) its good now. Sorry to be long winded but my point is it turned out to be a $25 sensor. Does the truck do anything out of the ordinary, does it act up every so often or anything like that?

The only thing it has ever done was the usual cam sensor X2, and it smokes quite a bit when you first start it in the cold (we usually average in the winter 20 to 25 degees) but I think thats because its just cold, it still starts well. I have a video on youtube of it starting in 18F degree weather with no additives or being plugged in, but you can see what I mean when I say it smokes. here

YouTube - Cold start of an 03 F350 7.3L dually

YouTube - Cold start of an 03 F350 7.3L dually

is the vid

[KnockingDiesel]

Nice truck. White smoke(if Im not mistaken) indicates air in the fuel line typical when it sits over night especially in the cold. Sometimes when it gets really cold Ive heard of guys draining the fuel filter bowl because when air is in the fuel line its really hard to start and sometimes on first start they die out in cold. I have good friend at the local dealer out here he use to be on the assembly line working on these engines Ill give him a call monday to see what he thinks. Good luck.