Ok I finally got some highway miles on my truck yesteday. It is a 02 CC LB7. So I figured that I would get better mileage, well at least a MPG or 2. Well I drove saturday a whole tank of fuel on the interstate going about 78 the whole way. And when I filled up yesterday morning on the way home I did the math and it was only about 13.2 MPG. So I figuered that was becuase I was going about 78 the whole way. So on the the way home I kept it under 75 and when I did the math after that fill up it was 13.8 MPG. So something isnt right, this is in an unloaded truck with one person in it. I did the fuel in the oil check the other day and didnt see anything. What all do I need to change? Fuel filter, oil and filter? anything else?

I have a 07 LBZ crew cab 4x4 and i got that mileage on my last tank. I think I got bad fuel because it ran like crud.
This tank already feels better

Maybe change gas stations?
I usually goto the truck stops; the crud gas i got from a cheaper valero station here in town.

Although if i go above 70 my milage is COOKED

Keep the RPM's below the 2000 mark, that is about 66MPH on my truck, if I go above that the milage drops alittle bit. Although I have never gotten below 17MPH and I usually average 20+ empty and keeping the rpm's below 2000. If I dog it, which is common with the program, just can't seem to get enough of that acceleration thing. I get on the average in the 18-19 range.

I would really hate to get 13 MPG, so MudMan, with the LB7 you should be getting better than that. Just for info, I can run 75MPH and still get the 18MPG I was talking about, so my milage does not drop off to bad. When I bought my rig, used in TX and on my way home, I did not watch rpm's or anything, and I still got 20.25 MPG on the first tank.

Well I am gonna change the fuilds and filters and see if that helps.

fill the tires up all the way to the max psi too.

You have a brake that is dragging??

jb

tires are good I just checked them the other day before I drove interstate.

Well I am gonna change the fuilds and filters and see if that helps.


Definately wont hurt anything..

Like cougar said make sure a brake isnt draging.

-Colin

anything over 73mph and MPG drops significantly...other wise 15 city/20highway

I just got back from a 300 mile tripp pulling a 15,000lb trailer and got 12.2mpg

i used to get 18, hen i put on my new tires. i didnt think that it would drop tht much, but i could be rong. is that the issue, or is there something else i should be lookin at? sorry to step on your thread, but i just want to shed some light on this issue.

I have 285s on it could that be a problem?

Are you taking the different tire size into your calculations, compensating for it? Biggers tires do effect MPG.

Truck came with LT24575r16, I put on LT26575r16 and the mileage was only off .3 mile for every 10 miles.

Well I think I figured out the problem. I was on the way too school this morning and the check engine light came on. So when I stoped I checked all the fluids and eveytthingn was ok. So I took it to and had the codes read and it was saying the Fuel temp sensor was off and that it had low fuel pressure. So the low fuel pressure is proobly the fuel filter so I am gonna change that out and then if that dosent fix the other one I will have to take it to the dealer and have the computer flashed and upgraded. So hopefully tthat is my problem and afte i get that done I will be getting normal mileage.

Just got back form 1000 miles in the poconos, averaged 17.9 with 80% highway, cruise at 70 mph.

i bought my truck and drove it home 300 miles with a western 8.5ft snow plow on it and got 16mpg going about 70mph

I have 285s on it could that be a problem?


Yes. You are going 7.8% farther than the Odo thinks. 12.8 becomes 13.8.

Also, the truck is pushing a taller gear and the computer compensates by adding fuel. That's worth 1-2 mpg also.