Fuel mileage comparison.....

[JGheen]

Hey guys, just wanted to get a quick comparison of your fuel mileages cuz I think mine was a bit down this last fill up and am wondering why. :{

I got 425 miles to about 31. 5 gallons which cam out to just under 14mpg. This was about 50/50 freeway and in town driving. The freeway driving is very minimal though as it takes up only 9 to 10 miles round trip of my daily drive to work. The rest is stop & go. Overall very short driving distances daily, probably 15-20 miles max. I really didn't drive it like I stole it during this last tank of fuel and only getting 425 miles to this last tank had me wondering.

Truck only has 21,600 miles and is running strong.



Thanks, Joe

 

[BrianJ]

Not sure where Castaic, CA is, but are you in a climate where they would have changed to winter fuel? That will drop your mileage 1-3MPG vs the summer blend.

 

[JGheen]

I'm in So Cal and that could very well be the reason. I always forget about that and being I usually get closer to 500 miles per tank that 1-3mpg drop would calculate out to be right.

Anyone else in So Cal notice a drop yet? I guess that would confirm the winter blend change.



Joe

 

[DZink24]

ULS Kero

If you thought that kerosene killed your mileage before, the new ULS kerosene is even worse! Enjoy! Thanks EPA!



The only thing wrong with your truck is the garbage that you are forced to put in your tank, and the ungodly cost of purchasing it.



Buh-bye to the 19+ MPG days.....

 

[HSpiering]

What tires?? That will make a couple MPG difference .

 

[JGheen]

What tires?? That will make a couple MPG difference .

Truck is stock other than the aFe Stg. 2 and PAC brake.



Joe

 

[MasterChief]

Actually for the type of driving your doing , and with the current mileage you have on the truck that doesn't sound unreasonable.

I had two major turning points in my truck's MPG. The first was at around 36K. My wife and I were coming back from a trip we made to Ohio in the summer when I though it would be a good idea to take a shortcut. (BAD IDEA). It turns out that state road 40 in the Appalachian mountains has some long %11 grades. Oh by the way my 5th wheel weighs 14. 5K plus all the goodies I had in the back of the truck, I would say I was around 23K total. To make it through the mountains I had to push that Cummins Motor like you read about in a “I can't believe it story. ” I just knew something was going to blow. As it turns out all the motor did was smile at me. Right after that my MPG went from 14. 5 to 17. 5 average. The second turning point happened this Monday when I had my computer software updated due to a cold air sensor reading incorrectly. Turn out that the check engine light coming on was a good thing, I am now getting 21 MPG after the update. Currently at 49K miles.



Mike

 

[BHolm]

It will get better. My '06 Mega started out getting 13. 8. After some long hard hauls, by 30k miles I was in the 18's, by 40k a solid 20.



You can't hurt these things stock. I ran mine into the wind for 8-10 hours one day pulling a big trailer, foot down 75 mph, 30 psi on the boost gauge. Like the man said, all it did was smile!

 

[Motorhead]

Just got back from a round trip to L. A. and back. Coming back I was carring about 1000lbs in the bed. I went 546 miles on 28. 3 gallons. Worked out to 19. 4mpg with only 3800 miles on the truck. Oh yea... I came back I-5 and went north over the Grapevine.
I am STOCK at the moment. Looking at a new SMARTY JR.

 

[JGheen]

I believe it will get better but I thought it already was during this summer of long hauls towing my sled puller with the gooseneck. Towing that 15K~(truck & trailer), I was getting around 13-15mpg on the long flat parts of I-5 and empty, on trips back home to Salinas, I was almost getting 20-21 crusing @ no faster than 70mph.

I guess it could very well be the winter blend fuel lowering it as well as the young engine mileage factor. Back when the sled puller was my daily driver, I used to see a considerable drop around Xmas time and into the new year. Only time and more miles will tell... ...



Joe

 

[Lifted Mega]

I don't feel your pain as for your mileage. Try being in my shoes with my 06 mega cab. Currently 30,000 miles and towing up and down calif. Just got back from towing a car trailer with a 1/2 truck and tool boxes (7000#) on it to east texas working it on every hill i came to. I got a best 8. 9 mpg running 65 mph loaded. To this day this truck on open highway (east texas) running 65 mph and pulling a empty car trailer 12. 4mpg. And if i run with empty towing nothing at 65 mph i can get 13mpg on a trip from bakerfeild to sacramento. This truck has been to a couple dealers and i've taken it to 2 independent shop and paid up to $200 at 1 shop in diagnostic checks and still no one can find anything. But the independent shops both agree this truck mpg should be much better than im getting. I have a 38 toy box that i took recently on short trip to the lake 41 miles round trip and the truck used 7. 4 gallons#@$%!. Thats a whole 5. 5 mpgOo. At least you guys are doing better than me. If this mpg cant get resolved i will be selling this truck as i hate to because i really love it other than the mpg.

 

[BHolm]

Nobody has suggested that the 4. 5" lift and big tires is your problem? I bet on a stock height suspension with less tire, you would find the milage would go way up. The amount of extra air you are pushing, and tires you are turning is what is killing the milage IMO.

 

[Lifted Mega]

Yes they have said that. I have a freind with the same truck with a 6" inch lift with 37" tires and gets 16. 5 mpg going to mommoth skiing. If his wife drives 18mpg. So he's taller pushing more air and turning larger tires. So what gives

 

[Lifted Mega]

Any other ideas what may be the problem that we all have been missing?

 

[JGheen]

I will be stumpped until this next tank of fuel runs out.



Lifted Mega, I had lifted my '98 12v with 37" swampers, 7" Skyjacker coils and DC long arms. I used to get great fuel mileage with that truck, around 17-20 on the freeway. I personally don't think the lifts or big tires matter much with these trucks due to the amount of engine torque they produce. Kind of like I would notice that running the A/C does nothing to fuel mileage on my '06 cuz the engine doesn't even know when it's on or off. Lift and tires will affect mileage some but not the drop we are seeing, IMO.



Joe

 

[WYoung]

Front end alignment?

The repair shop that worked on my truck after the wreck got to the point of aligning the front end and could not align it to factory specs. He said based on tire wear, it seemed I was out of alignment before the accident, and there was no damage that would have caused it to be so far out that it couldn't be corrected. He replaced the ball joints with adjustable ones and did the alignment no problem. I got it back and mileage has increased 4-5 mpg. I am at nearly 45K and completely stock. Before the wreck I was getting 15-16 mpg, now 19-20, and I got between 13 and 14 towing my 31' Airstream a couple of weeks ago to southern NM and back. Of course there were a lot of parts changed out, but I can't see them making the difference over the alignment. Here's what was changed (stock parts), draw your own conclusions:

A/C Condenser

Turbo Intercooler

Radiator

Transmission cooler

Ball Joints

Fuel pump/Sender unit (In tank)

Body parts and lights

 

[BrianJ]

Of course there were a lot of parts changed out, but I can't see them making the difference over the alignment. Here's what was changed (stock parts), draw your own conclusions:

Turbo Intercooler

Fuel pump/Sender unit (In tank)

Just two of the items that I can see making a bigger difference than alignment.



Proper alignment can make a difference, but to be so out of alignment to cause a 4-5MPG change in mileage you wouldn't be able to keep tires on the truck (due to wear), much less drive it anywhere close to straight down the highway.

 

[BrianJ]

Most of these posts about modifications (i. e. tires) aren't addressing the original post of a sudden CHANGE in mileage, not the overall low mileage. Since he doesn't mention making any changes to tires etc. for this one tank referred to in the post, the most likely candidate would be fuel related, i. e. change to winter blend, and/or dirty fuel, and/or filter getting dirty. .

 

[Hoagie]

I would also suspect that the fuel filter may be in need of a change/air filter possibly too. Fuel conditioner like Stanadyne performance may help too, to clean injectors and lube the pump. I use synthetic oil too and get up to 24 highway in summer probably 21 in winter.
Hoagie

 

[JGheen]

In response to the last 2 posts, the winter blend is most likely the culprit. I get my fuel from either of the same 2 places each time, and they are heavily used stations, so I doubt the fuel is "dirty. " Also, I change my fuel fliter every other oil change but my Pro Guard 7 is in need of a cleaning from the looks of the pre-filter. I also use Power Service Diesel Kleen @ every fill up.



Guess I will do some servicing this weekend starting with cleaning the air filter, rotating the tires and if there is time, change the fuel filter for piece of mind.



We'll see how that affects anything during this next week of driving.



Joe