Fuel milage Sucks!!

What is every body getting for fuel milage? I can't get better than 14.5 empty on the highway at 70 mp with my cummins and the 48RE and 3:73's. I'm running a Bully Dog Power Pup on tow mode. Whats up?

 

did you do anything to your exhaust or intake?

 

my overhead reads in the 24's when i get on the highway. i stay between 65 and 70, cruise on. my fuel tank seems to show about the same. i cant hand calc because my tire size is incorrect in the computer, so the ODO is off. theis puts the MPG average on the overhead off. it SHOULD be more MPG due to the truck knowing how much fuel it is using and not knowing how fast it is really going.

BUT, it should be back down because the Van Aaken is on low when i drive. so it really doesnt know how much fuel it is driving at all.

the past couple days i drove from Hellam PA to balitmore and back with a few side street detours and other stops, then i drove ALL over york county on the highway yesterday and then up to hershey PA. about 225miles or so, maybe more. used about 7/16th of a tank.

the nicer you are to it the better MPG you get. cruise is your friend, and staying at about 2k RPM is great. 19 to 2100RPM seems to be the sweet spot on my truck. with my tires 2k rpm is 65mph

 

48re, 4.10's, exhaust and intake and im seeing like 14-15 highway and keeping my foot out of it. just ordered a quad xzt in hopes of helping the mpg..

 

stock exhaust & air intake

 

I am getting 22 to 24 mpg my last tank I went 589 and that was fuel light to fuel light. and a hole bottle of P/S

 

Jake; I had the same problem as you-but got the PSM buick "cool hose" and cold air intake, lost the cat and stock muffler, added back a Banks muffler keeping the 4 inch stock pipes, TST powerMax CR (which advances the injector timing), and the Gear Venders OD (like a "7th" gear).
These mods made all the difference in the world for MPG. Went from 14.7 to 17.0 (and still climing) and I have a hell of a time getting er much over 1200 deg when towing compared to the 1450 I was getting before.
Remember, all this smog crap is forcing Cummins and the other mfg to retard timing (up goes wasted heat energy-down goes MPG and efficency.
In my opinion, what really made the biggest difference in MPG was the TST and it's timing advance features. But you have to try to aviod the temptation to mash on the thottle all the time like I do-as the TST really cranks up the power, and it's important to note that it does it through efficency improvement, and not by cramming more fuel into it.
Check it out, and let us know. Good luck, DD.

 

I see that you have the 04 and dually but, I am wondering if you have it lifted at all and are you still running the stock sized tires? The larger tires will make your readings come out wrong. Other than that I would have to say that your driving style may be to blame. Your fuel mileage does seem really low. I should think that your combination should be good for the high teens and perhaps 20 mpg.

 

No lift and I'm running Firestone Transforce AT tires. As for my driving habits...... I was trying to be as easy on it as I could to try and get my milage up. Didn't seem to make much difference.

Is there any merit to breaking a truck in correctly? Reason I bring that up is because I bought this truck with 112,000 miles, and the previous owner pulled a wedge type car hauler. Iv'e been told that the way a truck is driven the first 10 - 20,000 miles is somewhat the way it will run the rest of its life. I didn't know if that has anythiung to do with it or not.

 

well... the breaking in process question is like the question about the chicken and the egg... EVERYBODY has thier answers and nobody knows whos is correct. i know this though, i beat the everliving**** outta my truck EVERY day. including the night i bought it. granted i let it coe up to opperating temperature before i do and i let it cool down befor ei shut it off. regular maintenance is done on schedule...

others say be easy on it, others say be easy on it till about 1000 miles, then beat on it. all i know is mine is running just as good as another with 61k on it and my mileage is better than most.

 

You went 589 miles on one tank? I can only get about 450, and thats not pulling any trailers and taking it easy. And excuse my ignorance, but what is P/S?

 

i have gotten 580 on my truck with stock tires, 65mph on the highway, cruis set through passes and flats. i did it once a month or more. the secret is how you drive i think.

 

Driving habits

I firmly believe that driving habits are a big factor. I always get 18.5 - 19.5 on the highway and 17 - 17.5 on backroads and city. If my wife drives she always gets about 1.5 - 2 mpg less than that. She does not really reach higher top speeds, its just all about how you get there. My best tank was from Colorado state line across New Mexico at night 615 miles on one tank with 4 passengers and about 1500 lbs in the bed.

 

Driving habbits will be the biggest factor in your fuel mileage. As far as the break in period I think that seventy four blazer has it right. Now, I have had more than one person tell me that a vehicles computer has a learning curve. What I mean is that your vehicle may have been driven hard while pulling the trailer and now that you are driving it, it may have to relearn how you drive. I am not going to say that this is a fact just something that some folks have said. Personaly, I think that it would be a good idea to have the fuel system flushed and the filters changed. Keep driving it easy, reset the fuel mileage and see what that gives you. What is the worst that could happen?
LT.

 

So how is everybody calculating their milage? With the overhead computer or dividing actual miles driven by gallons of fuel used. The reason I ask is that I have found my overhead to be way off, 3-4 mpg more than what I get if I hand figure it. My computer reads in the 16-18 mpg, but if I only get 450 miles on a tank and fill it up with 30 gal of fuel, that equals 15 mpg, acording to my calculations.

 

well... i have not been able to hand calc in a WHILE since my tire size is off from the computer tire size. my overhead has read 22.6 to 24.1 in the past month. i have not driven a set mileage in the past year + so no clue right now. hand calc, miles over gallons is the way to go. overhead is WAY off. mine should be about on since i am using the correct amount of fuel at a slower than actual speed (how the computer sees it) but who knows. i am happy with filling up 3 times a month, so i dont really care how much i get. i do notice when i am nice to my truck i only have to fill up twice a month.

my mileage figures are from when i had stock tires on. i would drive from south campe pendleton CA through base then over to Pima AZ. one tank. drive around for the day or two i was there on the same tank, then fill up on the way out and arrive on the same tank.

 

Mileage

My truck is an 05 with 3.73. I run a PSM Cool Power intake with Amsoil EAA189 dry-flow filter, Cool Hose, TAG III, Aeroturbine muffler and a Smarty on level III (60hp) I did a 600 + mile trip on labor day weekend and averaged 19.2mpg running 60-70. It took us 8 hours to do the 5 hour trip up there due to kids and the truck was either running or idleing the whole time. Did quite a bit of in town driving while I was there as well. For my next trip I am going to add a 2nd Aeroturbine as I have gotten a lot of requests from guys to try it. We'll see what, if anything, that does for mileage.

 

fuel mileage

I was only getting 13.5mpg on my 04.5 H.O. and 8.0 on towing my fifth wheel until I upgraded with a 5" exhaust, cold air & triple dog with outlook. Now I'm getting 20-22 on hwy and 18 in city and the poweris amazing. My 97' PSD gets 22 hwy & 18 city regardeless. I love my cummins but the old 7.3's are still very hard to beat. My PSD has 280,000 miles and it is as strong as the day I bought it.

 

Jack rabbit starts kill the mileage. Best mileage is when you can keep the boost below 10lbs and using the cruise.

 

the only way to acturately calculate your mileage is to completely top of your tank ( I mean slowly fill it untill you cannot get any more fuel into it,even after you let it set for a minute). record the mileage reading.
When you fill up again you have to use this same procedure again. It will hold up to 2 gal more than when it shuts off at the station in a normal fillup. IF you want to track it for a few thousand miles, just filling up normal would be fairlly accurate, but if you are only tracking for 1 or 2 tanks it won't be.
Interesting, my overhead always reads 1 0r 2 miles LESS than the actual. overhead accuracy seem to change depending on how hard you drive the rig.