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<----Nice headlights!!!
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My gf has been driving my truck since sunday as I have been doing work on the van at night and she needs to be able to get around. Sunday I filled the truck up and she has gone to work everyday which is 8miles there, 8miles back. To the store a couple times, here, there, all totaling up to 268 miles. THings is she told me she needs to get fuel. I said 'Why'? She said "well the light thingy came on!" So we put thirty gallons in and that is about 9 mpg...:(:confused:

Last tank before that I avg twelve but pulled a 16,000lb trailer for about 100 miles so twelve was good. I even had a sticky hub the last three weeks! Now she drives it and this happens. I even asked her if she let it idle for extended intervals. She is saying no. She just called me and said she has gone 64 miles and is about at 3/4 tank.

WTF is going on. Where do I begin? Fuel filter was changed 120 miles ago. Oil hasnt been changed for three months but only has 1500 miles on the service. Tire Pressure?
 

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<----Nice headlights!!!
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Discussion Starter #2
My trans cooler is leaking but I check the fluid and I havent needed to add any. Fuel injectors going out?
 

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gf out drag racin lol
 

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Scab
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She is out blowing smoke and picking up dudes. Detune the truck and bet she will tell you something is wrong with it.
 

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<----Nice headlights!!!
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Discussion Starter #5
gf out drag racin lol
I wish! THat'd be hot! No she doesnt like it cuz its big and smelly. She said she likes to ride in it but doesnt feel sure parking and maneuvering it. Ive never seen her go over 55 in it. She beats the hell out of the Lincoln LS but is gentle on our minivan and my truck.

Anybody ever had an abrupt change in fuel economy? I wonder if its the MT tires on the highway? They have 30lbs air in them. I bought them a couple months ago and have yet to really use them over 45 mph. Its been mostly offroad use this year and it seemed like it was sipping fuel.
 

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Scab
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I wish! THat'd be hot! No she doesnt like it cuz its big and smelly. She said she likes to ride in it but doesnt feel sure parking and maneuvering it. Ive never seen her go over 55 in it. She beats the hell out of the Lincoln LS but is gentle on our minivan and my truck.

Anybody ever had an abrupt change in fuel economy? I wonder if its the MT tires on the highway? They have 30lbs air in them. I bought them a couple months ago and have yet to really use them over 45 mph. Its been mostly offroad use this year and it seemed like it was sipping fuel.
That could be your problem. Why do you have the pressure set so low?
 

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My other twin turbo...
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When I slap on the mudders here for winter, I drop an easy 1.5-2 mpg. They are stock size and I KEEP my fronts at 65psi and rear 55 year around.
 

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I wish! THat'd be hot! No she doesnt like it cuz its big and smelly. She said she likes to ride in it but doesnt feel sure parking and maneuvering it. Ive never seen her go over 55 in it. She beats the hell out of the Lincoln LS but is gentle on our minivan and my truck.

Anybody ever had an abrupt change in fuel economy? I wonder if its the MT tires on the highway? They have 30lbs air in them. I bought them a couple months ago and have yet to really use them over 45 mph. Its been mostly offroad use this year and it seemed like it was sipping fuel.
thats a huge problem.... they should have atleast 50psi in them.
 

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(520)465-7971
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Tell here to coast as much as possible. You can pick up an easy 2 mpg if you time lights and coast up to stops instead of using the brakes heavy. Its the only way I can get any kind of decent mpg in my truck.
 

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Scab
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My money is on driver error.... Only thing that needs changed or replaced is the foot over the pedal.
True. After all, she is a woman and is probably doing it wrong!
 

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<----Nice headlights!!!
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Discussion Starter #13
I trained her to drive it, and the other ones economically. Im gonna go put some air in the tires and then see again. Since those tires were installed it hasnt seen any real road time. Ive got 96 miles and 2/3 of a tank of fuel! That has to be it! Sh!t its gettin better fuel economy offroad! ha ha...Ill keep you posted as to what happens.

PS I told her unless she's pulling the skidloader you dont need anything above 2k rpm...its funny she'll let off to initiate a shift when it gets close.
 

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Gun Clinger
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How does your mileage compare to hers in our other vehicles? I can usually get 2-3 mpg better than my wife when I drive her car. She's only drove the Ex 1 time in two years. I won't let her cause she's rough on the brakes and taking off.
 

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Women brake late and accelerate harder than needed... That's probably part of it.

They also let their vehicles idle forever.

Also, they lie.

Is the truck tuned? Pull the chip.
 

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<----Nice headlights!!!
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Discussion Starter #17
I made her take me for a test ride and she is easy on the go pedal. Her braking sucks though. Probably why our van needed brakes at 60k miles.

Speaking of lying, sleeper, I told her the speedo is off 15 so she doesnt breach the 45mph mark on the speedo. A little white lie wont hurt.
 

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<----Nice headlights!!!
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Discussion Starter #18
She has driven another 100 miles today and is at the half tank mark so she used approximately 5 or 6 gallons since last night. use an eight of a tank today to go a hundred miles vs using 1/3 to go 96 as of lastnight! Wheeew...i was thinking $$ when I realized we were getting 8.654mpg yesterday afternoon. Ive got 45 lbs in the tires now. Might go up to 50(what the sidewall recomends).

How many miles do people with a truck similar to mine get out of a whole tank?!?! cc/sb 6" lift 120hp tune with exh stock injectors rollin on 37's with the stock 3.73 gear ratio. Anybody got a figure for me?

I drove mine on the interstates one summer in 2003 or 4 ish and even with a toolbox that weighed 285lbs in the bed I got, my personal best, 784 miles on 32.666 gal of diesel(not lsd, regular diesel) which is 24 somethingmpgs. Those days are Looong gone. Untuned, with the god-awful 40's and a 4" straight pipe job and s&b intake I was getting 20 on lsd. Now with ulsd(which always has some of that crappy bio in it) I get 16 or so...this last couple tanks not withstanding.

Im currently using the DieselKleen in the silver bottle. Is there something better? The stanadyne addy didnt seem any better for me. Im not totally sold on additives anymore. I used to see a difference when we went from dino diesel->lsd. When we went from lsd->ulsd my mileage became sporadic enough I didnt know what was causing it. NOW with buy-mo(bio) diesel it seems to be gulping it! A local farmer who is HUUUGE was talked into trying bio in their tractors and p/us and they agreed to try it for three months. They fired their oil guy for it as it cost them a years maintenance costs in a month in plugged filters and lost mileage. I feel Im not alone in hating this crap we're forced to buy.

What is the solution? Make my own? If bio blended crap was cheaper Id not bitch but at 291 vs 261gas its bs. I know of one Shell that sells non bio blended ulsd. All the others including the one by my own house that sold ulsd have gone to soy bio..I see these blends pushing us into the sub 10 even with careful driving. What can we do? If diesel is sooo bad gasoline should be illegal to posess, no?

I dunno, Im just tired of getting a$$raped for crappy fuel. I wasnt happy when lsd started to cost more and even when ulsd started showing up my stance was "still better than gasoline". Now I wonder where they will stop?

Or do I need a 'new' truck? Do I have to spend 60k to get a truck that'll sip garbage fuel?

Rant over...need input
 

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I'd drive it for a tank and see how your mileage compares. Could be her or could be something else. Eliminate the driver and go from there. Also 30psi is way low on the tires. Are they load range E?

My wife actually gets better mileage in my truck than I do. She keeps it under 65 on the highway and stays out of the turbo. She gets worse mileage than I do in her SUV.
 

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1. Put the tune to stock
2. Air up the tires to 50 psi (I run 100 psi)(These trucks MPG is VERY sensitive to air pressure - I suspect bigger tires even moreso)
3. Check for dragging brakes
4. Check front end alignment

After that, suspect the driver.

'Tain't the fuel. I get good MPG on ULSD.
 
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