gas mileage again...help!

[evomind]

ok, stock my h3 was getting 225 miles from full to low fuel light..abt 20 gallons. thats 11.25 miles per gallon.
now with the 35's on there, im getting 200 miles in the same span...abt 10mpg. i told the sales manager abt this in passing, and he said that was waaaaay low....even with big tires. he told me to tell service abt it, but not sure what they would do. i havent seen any gas leaks.
any ideas?
btw...i drive both highway and city, i dont baby it, but i dont floor it at every light either.
thanks

[evomind]

ok, stock my h3 was getting 225 miles from full to low fuel light..abt 20 gallons. thats 11.25 miles per gallon.
now with the 35's on there, im getting 200 miles in the same span...abt 10mpg. i told the sales manager abt this in passing, and he said that was waaaaay low....even with big tires. he told me to tell service abt it, but not sure what they would do. i havent seen any gas leaks.
any ideas?
btw...i drive both highway and city, i dont baby it, but i dont floor it at every light either.
thanks

[The Green Lantern]

- you know, that's my problem too. I'm getting 250 miles average before I re-fuel, mostly city driving though (90% city - 10% highway).

[H3 Hummer]

Most people average around 14 or 15 - towing, up mountains, etc. On average 13 - 16. 11 is kinda low but pretty sure no fuel leak, you would smell it.

Why don't you fill up jump on the freeway go about 20 miles at 60 top, fill up and see what you get. If it is flat I would say at least 15 MPG.

[shipbldr]

Well, ah, considering the number of 6 MPG tanks I've had... I'm not that surprised.

Few things...

1) Are your tires properly inflated?
2) Is the truck broken in yet (2500+ miles)?
3) Any toys on the roof? (My pelican cases cost 1 MPG+)
4) Try staying at 65 mph. I loose a lot of milage once I get past 65.
5) ..and my secret for getting a ROCK STEADY 24 mpg: Drive the Nissan Mini-van!

Hope this helps some...

[MarK M]

just came back from a one day trip to tahoe.

loaded full tank with 87oct. got the rig up to 330miles before loading.

your tires are probably giving you the bad milage.

[f5fstop]

You did take into affect that the tire diameter affects your fuel mileage calculations.
Larger than normal tires will make a speedometer indicate LOWER than actual speed; thus it will not give an accurate reading of how far you have driven (odometer).
The speedo might show 70, but you are really doing 73; therefore, you have driven 73 miles in one hour, not 70 as shown on the odometer. (These were just an example from my Jeep where I went two sizes larger, I have no idea how far off your speed is, but is probably is off something due to larger tires.)

In addition, larger diameter heavier tires take more energy to spin and will lower your MPG.

[HumbleAg]

I'm still getting 16.5 to 17.5 on every tank. I have the Bridgestone 33's.

I did discover that my odometer is a bit overzealous by about 3% (when I go 10 miles it actually reads 10.3 or so), so that makes the actual mileage a bit lower, but still better than 16.

I am a very gentle driver, but it sounds like there is something wrong with yours if the mileage was that bad before the 35's.

[evomind]

right guys...i know the bigger, heavier tires will adversly affect my mpg, thats why i pointed out that bone stock i was getting somewhere in the 11's mpg....~20 gallons and 225 miles stock...that was still way low. i have 4700 miles on it. my 4 wheel specialty shop and the dealership were both very surprised that even with the big tires as my truck sits, im at 10 mpg.
i should have bought an h2.

[shipbldr]

Are the tires wearing evenly on your truck?

Is there a lot of soot on the exhaust pipe?

I agree with you that something isn't right about 10 mpg number...

I am wondering if you are running a massively rich fuel mixture... of if one of your wheels is WAY out of alignment...

Are you 100% sure your truck shifts into overdrive?

Check the Cat converter for clogging yet?

I'm runningout of ideas here... that number is WAY TOO low...

[HummerJim]

That sounds exceptionally low! With over 31,000 I'm averaging close to 17 mpg with 60% hwy, 20% city and, 20% dirt and gravel country roads. The worst mileage I've seen was 10 mpg in Dillon, CO offroad on a hot day at high altitude with quite a bit of low range when new(low air density/high pressure altitude for the engine), and the best in the high 19s on the highway with a tailwind, 45F, and at close to sea level with the cruise on 65mph.

[evomind]

thanks for the help and concern guys....i love my truck, but the gas mileage is kinda killing me. my other 2 cars are performance/sport cars and theyre misers compared to this thing..
shipbldr,
my tires are wearing evenly, and i just had 2 alignments...1 when putting the lift on, and another after mudding, knocked alignment out of whack. the alignment is good.
ill have to check the exhaust and the cat...actually, ill see what the dealer tech says as it has to go back in again for the check 4wd system light again.
i just cant figure it out. i was gonna do some more work to the truck in mods, maybe s/c, but now im just thinking ill wait till the v8 comes out and trade up. i cant see my gas mileage getting any worse...
thanks guys

Running stock 32's on the street, the lowest I've seen is 14.25 mpg. I've been checking my mileage at most fillups for 6 months and average about 15mpg. Mixed suburban driving mostly.

S.

[Grandman]

Good God man i got 10.4 mpg out wheeling .

17.9 was my best tank so far that was 2 lane highway at 60 mph .

Your not doing any harm to have service look at it , maybe theres a code they can find . If it is running in the cold loop it will burn far more fuel . Somthing like a temp sensor can cost you mileage .

[H3HUMVEE]

I'm getting around 20 to 21 mpg every tank with mine and a couple of tanks I got 21.6 and 21.4 with a mix of city and hwy driving ... 5 speed with 32 tires, try to keep it under 65 mph.