Nobody warned me about the MPGs on these square bodies!

[Hilllbilly]

] I’ve got an 06 2500 4wd Megacab w/ 6spd & 3.73’s, I’ve never gotten better than 16.5

16.5 is horrible for these trucks... Sounds like you truck really has something wrong with your truck. Your injectors completely shot and leaking or something, or you got a fuel line leaking onto the road

Mine is hand calculated, From Boise to Salt Lake city.
Most people get over 21 mpg on the highway keeping it under 65 mph

I have 2 5.9 cummins diesel trucks since 2001, 24 years.
A '99 2500 4x4 auto trans with 3:50 gears,,, and a '05 3500 sht bed 4x4 auto trans with 3:73 gears .
Both are stock engines , no hot rod tuners or rick racer turbo crap. Just gauges, always maintained well, and one has a built trans.

 

[PrairieDrifter]

I get 11-12 with a wore out stock bore 350, 700r4 and 3.73's with 35's. A little more tuning and I could get more for sure. I'm also not too gentle with the throttle lol

I'm definitely undergeared for my horsepower lol. That's ALSO in a suburban with a 5 inch lift. A fresh mild 350 and 4.56's for me I bet I could do 16-18.

 

[pinballlarry1]

Years ago, had an '89 v2500 suburban 350 tbi, th400, 4.10 gears, stock size tires. Gas mileage was 10-11 under every condition. Really made little to no difference going fast or slow, town or highway, even loaded or empty. It would drop to 9 mpg when pulling a 16-foot, loaded enclosed trailer.

 

[Turbo4whl]

@WranglerTJForum You may have forgot, these trucks were designed in the early 1970's. Gasoline was 30 cents a gallon. 16 gallons is kind of small, but the short beds were the compact trucks of the day. 20 gallons for large cars and trucks was the norm. Heck, GM just finally move the fuel tank out of the cab.

 

[nvrenuf]

@Hilllbilly I’ve owned mine since new and the mileage has been pretty consistent, there’s nothing wrong with the truck. A couple of quick searches on Cummins forum and DTR show my results are fairly average.

 

[77Dmax]

Dodge guys cant do math! Every cummins out there gets 25 mpg and makes 500 hp. Just ask.

 

[Redfish]

16.5 is horrible for these trucks... Sounds like you truck really has something wrong with your truck. Your injectors completely shot and leaking or something, or you got a fuel line leaking onto the road

Mine is hand calculated, From Boise to Salt Lake city.
Most people get over 21 mpg on the highway keeping it under 65 mph

I have 2 5.9 cummins diesel trucks since 2001, 24 years.
A '99 2500 4x4 auto trans with 3:50 gears,,, and a '05 3500 sht bed 4x4 auto trans with 3:73 gears .
Both are stock engines , no hot rod tuners or rick racer turbo crap. Just gauges, always maintained well, and one has a built trans.

Wow! That must be why Ford and GM cannot sell any diesel trucks! They just cannot compete.

Either the air is thinner where you live and trucks get better mileage or your diesel fuel is better. The only Dodge/Ram Cummins I ever ran that ever got better than 21 consistently had a tuner or programmer installed. Every 5.9 I ever drove or rode in was in the 16 to 19 mpg range consistently. And I was fine with that.

I will say that when I made a trip through Colorado and was running at high altitude my Duramax did get waaaay better fuel mileage than it normally does down here in Swampy Flatlandistan. I can see how someone who lives in a different section of the world could get significantly better mileage than we see down here.

Back On Topic:

My '87 4wd with 3.42s, 4 speed manual, TBI 350 and 33x12.50s is good for 14 to 14.5 mpg on back roads driven gently. If I am driving it in town and/or to work it is doing good if it gets 10 to 11.

But I look Very Good doing it!

You must be registered for see images attach

 

[77Dmax]

I get 16-18 with mine. 95% of my driving is rural/back roads. Its a constant 18 on the highway.

My 93 two door Blazer got 14 in town and 16 on the highway. In the winter it would drop to 11.

 

[ChuckN]

Since mine is a street cruiser with a mild engine, I’ve never looked at anything but the fuel gauge to make sure I’m safe to get back home. In just about every direction but one, I have an ethanol-free station within 35 miles to refill. I accepted before I even got it on the road that the mileage would be terrible. Even in stock form, these trucks had low mileage and were produced when gas was less than a buck a gallon. Still sucks to get stranded though!

 

[nvrenuf]

@Redfish i was hoping to see your sweet truck again at CTC but work has gotten in the way and I won’t make it.

 

[fast 99]

Being as though this is Wyoming I'm almost always fighting wind (sometimes lots of it). Since mine is a '73 and doesn't have baffled tanks, I'm wondering how much fuel is actually left in there when it sputters and dies.

Almost 0, when I run a tank dry it will take 20 gallons to fill a 20 gallon tank. Really depends on close pickup is to the tank bottom.

 

[Ricko1966]

Almost 0, when I run a tank dry it will take 20 gallons to fill a 20 gallon tank. Really depends on close pickup is to the tank bottom.

It's a little different with TBI if the tank pickup gets uncovered for a seconds they'll die but restart. You need to keep about 1/4 tank in it.

 

[fast 99]

It's a little different with TBI if the tank pickup gets uncovered for a seconds they'll die but restart. You need to keep about 1/4 tank in it.

And to cool the pump, I like people who run injected vehicles nearly out. We call them customers. Today almost any in tank pump repair starts at $1000.

I thought the OP had a 73?

 

[Ricko1966]

And to cool the pump, I like people who run injected vehicles nearly out. We call them customers. Today almost any in tank pump repair starts at $1000.

I thought the OP had a 73?

You maybe right I'm don't remember the year but he's running Sniper TBI. I'm assuming he's running an intank pump in an early tank,but no matter what,intank or inline he's going to kill that pump in very short order starving it for fuel.

 

[gmbellew]

You maybe right I'm don't remember the year but he's running Sniper TBI. I'm assuming he's running an intank pump in an early tank,but no matter what,intank or inline he's going to kill that pump in very short order starving it for fuel.

yup. I keep my TBI above 1/4 tank unless its some sort of emergency situation. and modern EFI vehicles should be the done same way