My trucks specs are in my sig. My gas mileage is dropping big time. I just went on a 735 mile trip. First tank of gas was just over 19 mpg, 2nd tank was just over 17 mpg, and the 3rd was under 17mpg, all on highway.

-First tank was around 70mph for the most part
-2nd & 3rd tank was around 75-78mph for the most part.
-Driving around town now I have put about 55miles on this tank and am already around 3/4 tank.

I usually get around 17 around town and around 300 miles to a tank.

What happened? Any help would be greatly appreciated!

-Mike

 

For every 5mph you go over 65mph you loose 2mpg.

Around the city your MPG can differ a lot, it all depends on the way you drive and how much you stop & go.

 

That's not entirely true. last year I was on the road for a while doing around 75-80 and got just under 22mpg(with stock tires) when I was getting 18 around town.

 

I get 14-15 consistantly in town with 33's and 4.10's. Could have got into some bad gas too.


How long ago did you change the fuel filter, air filter...

 

Fuel filter has been about 30K and the air filter in a MAC cone filter and it is still fairly clean, that was the first thing I checked.

 

But that is on stock tires darling.

Now that I have changed my trans fuild I get almost 20 in the city (usually just get 16-18 though), stock gears on 33s. Then again I only max the truck at 2500rmps when accelerating :) everyone behinds me gets so mad, races around, and we sit side by side at the next lgiht. I do have a heavy foot some times, it brings me down to about 10mpg sometimes.

 

Trigger... ithnk you just got a bad batch of gas. That happens to me sometimes. When I don't go to chevron and go somewhere else, it happens.

 

Ive been getting varied gas mileage lately too. I havent driven enough to get a real good average, but out of the 4 tanks since my lift/tires, my mileage has ranged from 13-16 all doing the same driving, same speeds, on the same roads etc. etc.

I really think its the gas itself since nothing i do has changed and neither has my truck

 

Don't feel too bad,I only average 14mpg city wise taking it easy on 235's.

 

I get about 16 in the city, so you are doing pretty good.

 

You probably just got some bad fuel. Run a bottle of Red Line SI-1, to give your fuel system and injectors a good cleaning. By the way, at 30,000 miles that fuel filter is due.

 

YUP! Trigger, while your doing your fuel filter, you might as well pop that grille off and paint it while your at it.

 

I am planning on replacing the grill here withing the next two months. Believe me, I know it needs to be done. I think I have a fuel filter sitting in the garage back home in GA. I'll have to dig it out when I get home. Thanks for the help.

 

keep in mind theres alot more of the e85 in our fuel now. and yes 55mph gets you a set mpg, but 65 mph will be 10%less mileage and so-on 75mph 20%less. stock tires will get drastically different mileage than bigger sizes at those speeds. I refered to the e85 because is cleaner and combustible so teh govnt recommends it but its less combustible than gasoline so less mileage more cost.

 

are you serious?! WOW i get 13 mpg city with 285/70r17 in a v8 expo. Might wanna check your gearing.

 

eh, i get 13.7 with 255's on highway and city, so somtimes u just get skrewed.

 

all i use is chevron, if i use crap like valero, or circle k my milage drops off like 4-5 mpg

 

yea the govnt recommends it....has no one figured out that the government is making too much money off of gas to drop the prices? thats why the prices keep going up

but there could be numerous reasons for your mileage decrease. have you lost any power?

 

I can only get about 215 city miles to the tank and thats with a K&N intake and a gibson exhaust

 

due to my wheels (steel) and 32's and rollbar and brushguard, my truck gets about 13 mpg. weight = poor mileage.

 

atleast i'm not the only one getting horrable mileage

i get 13-15 and if i can get to 60miles to the first 1/4 of the tank i know i'm getting about 14-15mpg. in the winter i was getting 14miles to the first 1/4 haha

i cant wait to get rid of my truck, but i love it so much so thats why i have a tiny for sale sign on it lol

also i just got an estimate on stock tires Yokahama geolander A/T 245/75R16 and it was going to be 625$ mounted and balanced so i thought id just keep my tires because 600$ is to much and i proably wont gain anything on the milage to off set the price.

 

My gears are 3.73 , My dad's chevy tahoe gets better gas milage then me with a 5.3L V8 in the city.

 

oil change perhaps?

 

Just had it done 2 weeks ago.