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Discussion Starter #1 (Edited)
Just drove home from oklahoma, i usually get around 550 to a tank on the interstate, Anyway i got only around 400 miles on both tanks of fuel! What gives? The only thing i've done is put that rail cap on and a guy wouldn't think that would cause that? I put my 315's on before i came down and got around 17-18 so its not that. Any ideas? i change fuel filters religiously so i doubt thats it. Oh yeah, one tank was fuel out my drag tank, and was was from a gas station.
 

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bad diesel? also clean your air filter.
 

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is that going from the overhead? or did you know the exact mileage?

because if your speedo aint correcected from the bigger tires, your goin more miles than its readin....
 

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Discussion Starter #4
i always use my gps for speed and mileage. i think i wind up driving like 40 or 50 more miles than my trip says to a tank. I just looked at my air filter before i left, still clean so i closed it back up. I'll have to buy another tank and see what happens.
 

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Discussion Starter #5
And yeah my overhead says i get 19 or 20 and like 700 miles to a tank, I wish
 

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Mine has been all over the place lately... one week its 550 next week is 410-430.... and its all out of the same tank....
 

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Discussion Starter #9
400 miles to a tank is friggin horrible! My filter is always changed but i'll do it this week when i do my oil, like i always do. It must have been windy or somthing cause what else would cause this?
 

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when i go through a tank in town i get 469-496miles(16.6mpg/28.273gal). and when i stay on the hwy. i get 574 miles(18.87mpg/30.446gal) and still have a 1/8 left. when i travel i write it all down and keep all reciepts. i need to change my filters soon too! all without the smarty, we'll see how much it saves when i go through afew tanks
 

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who pumped your last tank, and if it was you, did ya make sure the tank started at zero ?. some of the older pumps would let ya leave them on after a sale, then next guy would start the pump, and pay for the fulel he got plus the fuel already taken last customer. just a thought./
 

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I've had that happen to me too...its not permanent.
Most likely causes and in no particular order:

#1 Fuel quality - I can't believe this is true, but lately I've been getting better fuel mileage from the grocery store discounted fuel then I do from the Shell truckstop (119 and I-25 for those who know the Longmont area). But typically, truckstop fuel is the better of the two. The Conoco gives me better mileage also.
#2 Outside temperature - the colder it is, the crappier my fuel mileage is. Over the winter, 450-500 miles. Once we started having 70 degree weather for those few days, 550+ miles on a tank (yes...same route to work...same everything).
#3 City starts/stops while you were in town prior to heading back home.
#4 Wind direction. Heading to Ann Arbor, I do pretty good...at least 500 a tank. Heading back home from Ann Arbor, average is more like 450-475.
#5 Speed differences. When going on vacation, i find myself pretty kick back for the first few hundred miles. A couple of tanks into it, depending on where i'm going, I might find myself setting the cruise in the 80-max 85 range (especially around SLC Utah). Coming home...I just want to get home...so no cop, no stop.

Not to say that any of these apply to your situation, but I can only say that it applied to mine and that's why I piped up and thought i'd mention it.

TTFN
 

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I've had that happen to me too...its not permanent.
Most likely causes and in no particular order:

#1 Fuel quality - I can't believe this is true, but lately I've been getting better fuel mileage from the grocery store discounted fuel then I do from the Shell truckstop (119 and I-25 for those who know the Longmont area). But typically, truckstop fuel is the better of the two. The Conoco gives me better mileage also.


TTFN
I have noticed this too, when I am in town there are only a select few I fill up in... I filled up today at the farm instead of my tanks at the ranch... maybe it was the temp drop within 30 min but I noticed a significant power change... I begining to wonder if I have some SH!Ty fuel in my tanks.... all of them are clean ond filtered 4 times before it going into my tank... we will see when I head to the car show tomorrow and pull 110 on the Odo...
 

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Discussion Starter #14
Well it was getting jurastically colder once i got out of oklahoma, pretty much from 65-70 to 30-35. so maybe that was part, it is always windy on I-35 through iowa, another part. But still seems pretty low to me, I'll have to report what happens when i go back to work seeing that i only drive around town when i'm home.
 

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i just fueled up from driving highway at 70 and secondary roads at 55-60, and doing the occasional rompin on the throttle and got 450 miles on 1 tank of fuel with still a little more to go and hand calculated 14.5 mpg
 

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I filled up at the farm this weekend, different fuel supplier, and got much better milage and performace out a it.... So to say the least I will be switching over to that fuel supplier once I burn through the last 1000 gal I have...
 
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