Engine/Transmission (1998.5 - 2002) 400 miles is all I get on a full tank of fuel...is that normal?

[VIPERBLUELX]

I know 13-14 mpg isn't absolutely horrible I don't guess, but I hear all these high mpg numbers from other diesel owners. All my mods are in my signature, the truck gets right at 400 miles on the trip odometer each time before I have to fill up. This is about a 70/30 mix of highway/around town driving. I set the cruise at 80mph on the interstate which puts the RPM's at 1900ish with with 3. 54's and 35" tall tires. I have all the tires at 40psi, just had an alignment, air and fuel filters are new. Any ideas?



Also I've tried running the Comp on 1X5 also and the mileage doesn't seem to change any at all.

 

[JFlagg]

Do you ever notice if your mileage goes down when the stations switch to winter fuel? I know my 02 is making about 15 mpg right now. I usually lose about 1 mpg on winter fuel. Most of my driving is city though. I have the 3. 55s and 35" tires too. I usually run around with my Comp box off though. I think your automatic might hurt you alittle, I've always heard sticks make better mileage. I also usually cruise about 70-75 on the highway, depending on traffic, though it seems to run smoother around 80 with the 35's. Personally I think you are right in the range for our motors with the mods you have. Hope that all helps...

 

[analog]

I notice I get better mileage when I set cruise to 65-70 as opposed to 80. 80 might get me there faster, but it does cause a noticeable hit on fuel mileage.

 

[DPelzl]

I would not be happy with that at all. I run smaller tires 265/75/16 and my truck is 2 wheel drive but i can go over 800 miles on a tank. I get about 26 mpg on the road running at about 75-80mph and about 19mpg around town. My buddy has a 4wd with 265/70/17 and he gets about 21-22 on the open road. Doesn't sound right to me larger tires and 4wd shouldn't cut your milage that much, but a heavy right foot will!!!!

 

[RickFox]

I hear all of these high numbers and I can't believe it I had a 02 with 6-speed, Juice, 4" exhaust, and a holley blue lift pump. I ran 285/75 R16 and the BEST I ever got out of that truck was 17. The 2000 I have now I am SUPER excited when I see 14-15 and that if only when it is ALL highway driving.

 

[JTHosler]

Mileage

When I fill up, I am usually about 420 on mileage and usually putting around 28 Gallons in. Most of my driving is 55 - 60 for a 30 mile round trip to work everyday. Hope this helps.

 

[Regcabguy]

Big tires.

I think the 35's w/aggressive tread are your main culprit. I got 14mpg with my '99,DTT,EZ and mach 1. 6's. In addition,I hauled a 2000# popup on my back 24/7. I'm only getting 12. 5 mpg. with my stock '07. It's got a long way to go before breaking in.

 

[KKunz]

How far can you guys go once your low fuel light comes on? Also I think the tanks on a short box are smaller so that might be a factor.

 

[KennethS]

I never got the mileage that everone else does either

I get 14 pulling a car trailer and the best is 16 with my 2006 dodge automatic diesel. I still love my truck. I am67 and everone pass me on the interstate I never go over 70 and 65 most of the time and My truck is a two wheel drive.

 

[Cryppie]

Well guys, I've been on both sides now... my '99 2500 QCLB 4X4 got at best 17. 5 hand calculated, babying the throttle. My new to me '01 2500 QCLB 4X2 gets 22+ cruising at 68mph, again hand calculated. I know there is some power loss through transfer case/front axle, but I believe that each individual engine gets varying mileage based on how it was initially broken-in. In my case, when I got my '99, I was not yet a proponent of "drive it like you stole it, and with a metric butt-ton of weight behind you". My '01 was a Texas ranch truck with a GN hitch, and I suspect it was worked in well from day 1. Bottom line is, on a 2nd gen truck, you are going to have to live with the mileage it gets, good or bad. Just my . 02.

 

[JDumont]

I get around 13 mpg. The only time I ever seen 15 was on a trip. But then I do have a heavy foot.

 

[LOtero]

do you guys have your spedo corrected with the bigger tires? If not your mileage is off, witha taller tire you are going farther with one revolution than with a smaller tire. so 14mpg is 15-16. befor I put my 315's I was getting 380milesa tank now only 320. thats filling at 1/8 tank.

 

[ACuster]

I have a stock 99 qaud cab. 4:10 gears, 285/75. i've been getting 18 mpg on 30 gal tank. Includes town and highway driving.

 

[JCutter]

With everything in my sig i get 14-16 with 33 in tires. in southeast indiana. 16 is pushing it but i got it when i drove to texas. 14. 5 is the norm for me. roughly 380 miles at the 1/8 th mark or just below.

 

[Doug1810]

40 psi seems low on the tires i run 33" tires at 70 psi mud tires and i get 16 mpg with my stock traanny that slips alot darn t. c.

 

[terrywerm]

I've currently got 265/75R-16E tires on mine and typically get 18 - 19 during the winter, and 20 - 22 during the summer months. I drive about 50 miles round trip each day to work, about 3/4 freeway and 1/4 city streets, and I usually run about 70 MPH, depending on traffic.



Some years back I ran some 285/75R-16 tires with very aggressive tread on them. They were noisy, looked nice, and I liked them for off road / soft ground, hated them on slippery / snowy roads, but the corrected fuel mileage with those tires ran about 13 - 15 in the winter and 16 - 18 in the summer. After going to the less aggressive 265's my fuel mileage definitely increased, and with no other changes to the truck or my driving habits. Fuel mileage while towing was also slightly worse with the 285's but the difference was not as significant.



I also found that staying at 70 MPH or below helps to keep mileage up, and I also find that my acceleration habits can make a difference. Accelerating moderately (about 10 - 12 lbs of boost) through each gear seems to be the best. I assume that is because I am getting into a higher gear and up to cruising speed a little quicker as compared to accelerating too lightly or, worse yet, too heavily.



Just my experiences / observations.

 

[SHobbs]

Original VP44 got me as high as 21, the new Vp44 is doing good to get 19. Hopefully that will improve. This is shifting under 2000rpm, light throttle and setting cruise at 62 every where I can. If I get anyfaster than 65 look out, the mileage drops.

 

[JFlagg]

do you guys have your spedo corrected with the bigger tires? If not your mileage is off, witha taller tire you are going farther with one revolution than with a smaller tire. so 14mpg is 15-16. befor I put my 315's I was getting 380milesa tank now only 320. thats filling at 1/8 tank.

I don't know about anyone else with bigger tires, but I use the GPS in my truck for mileage. I found my warranty lasted longer if I didn't correct my speedo Managed to get a new 6th gear synchro when I had 98K on my truck for free, if they knew I had been running 35's since the truck had 10K they would have done the math and realized I was actually around 107K. Would have had to pay to get the fix done, that would have sucked!

 

[kbond]

I would not be happy with that at all. I run smaller tires 265/75/16 and my truck is 2 wheel drive but i can go over 800 miles on a tank. I get about 26 mpg on the road running at about 75-80mph and about 19mpg around town. My buddy has a 4wd with 265/70/17 and he gets about 21-22 on the open road. Doesn't sound right to me larger tires and 4wd shouldn't cut your milage that much, but a heavy right foot will!!!!

Gotta love these guy's. Keep hope alive. You didn't say how much larger your aftermarket tank is to get the 800 per tank? Everyone on here knows it's impossible to get 26mpg... especially @ 75-80mph. Maybe you got a 4bt by accident in your rig. Could have been a factory mis-hap.

 

[Dieselram]

just to show you how much your driving style effects fuel milage i have gotten as few as 360 miles on a tank, or as much as 505 with the truck in the sig