Sucky Fuel Mileage

[E7mack96]

I have the truck mentioned below, in my sig.



The problem is the truck is only getting 17-18 miles per gallon. This is unloaded, steady state 65 mph. I am putting 500-600 miles on the unit PER DAY:--) . If I can up the mileage some, I will same some serious CASH



Any Ideas???

 

[illflem]

You should be happy with that kind of mileage, many 24 valve 4wd trucks get worse. If you really want to jack your mileage up trade it in for a 12 valve, mine get 22-24 hiway unloaded.

 

[shendren]

Illflem,



roughly, how fast are you driving on the interstate to get the 22-24mpg?



thanks. scott.

 

[WyoJim]

I had a 12 valve 5 speed that got 22mpg at 70 on the highway. A regular cab that weighed 5800lbs.

I now have a 24V Auto Quad Cab that weighs 6700 lbs and gets 21 mpg at 65 mph. And it will run over my old 12 valve. Smoke that illflem.

 

[Happy Camper]

18. 5 is the best I have gotten. I will have to be satisfied with that. 38k and little change.

 

[klenger]

E7mack96



What's your axle ratio?



If you want better milage, drive a V10 for a month and then go back to the one you have.

 

[illflem]

Scott, running at 70, after 2000 rpm (around 75) the mileage takes a dive. 27. 6 has been my best mileage.

WyoJim, you've got a rare 24 valve there, better hang on to it. Just remember to carry an extra lift and injection pump...

 

[LSMITH]

illflem, mine gets 22+ at 60 MPH. They are not all bad for economy. I would suspect that you are getting that kind of economy with the 2500 you have anyway.



I think that 18 at 65 with a 3500 is about as good as a guy can expect though. It is decent really.



EDIT: oh yeah, 90K+ miles on original lift pump and injection pump. The injection pump is not an issue of you monitor fuel pressure. Changing a lift pump every 100K is much preferable to adjusting valves every 30K IMO too.

 

[E7mack96]

response to axle ratio

I have a 3. 54 ratio

 

[WyoJim]

Hey illflem... . Is there a 24 valve pump list similar to the 12 valve KDP jig list? What happens if you don't get the jig and the Killer Dowel Pin kills you?



We have one 24 valve that has hit 23 mpg regular. MPG is mostly in the application of the right foot. Its an Automatic too.

 

[The Sequel]

I usually average just over 18 with about 75% freeway at 65mph and 25% in town. Sounds like your's isn't too bad. Very minor hills can really take a quick toll though.

 

[danglin5]

got a 2001 2500 automatic 4x4 only gets 15city and 17 hwy.

wish i could get better milage.

truck is not loaded. empty 99. 9% of the time.

 

[dsnook]

I have 1400 miles on my truck, and I have gotten 17. 5 mpg on the last two tanks. Most of my driving is city-country backroads. This is MUCH better than the 10mpg I was getting with my pherd.



read-one very happy guy!



"D"

 

[Vaughn MacKenzie]

Even with some winter blend fuel I have been getting pretty good mileage this winter, better than last year. My 2wd rig with my junk and capper weighs about 6700.



On a RT to Bend Oregon I turned in 23mpg running 65-70mph. I only had 3-4 blasts over 80 passing people. For the most part I took it nice and easy. This was with a mix of 25% #1 and a normal dose of Stanadyne.



Unless I drive like a maniac I can expect to better 20mpg on any highway trip. To drop below 20 I have to drive close to 80mph and/or make use of my CPC box & injectors often. I am pleased with the mileage I get, especially since my engine has never idled smooth and has poor drivability/surging issues. When I burn a whole tank in town it rarely drops below 17.



Vaughn

 

[RHARVEY]

I have one of the under valved trucks with a 5 speed and I get between 23-25 freeway. . at 70 mph with cruise. Back and forth to work with some city, I get 20-22. 7.

Nothing has been done to the plate or injectors. All that I have done is a straight pipe 3" and Scott's air induction system. .



Rick

 

[Pit Bull]

My truck see sig. weighs around 7600 lbs with the truck empty other than the driver. I get 19 - 20 summer fuel on a highway trip, depending on my speed. 19 at 70 mph or above, 20 at 65 mph and below. Winter fuel knocks it down 2 mpg. I think you are getting good mileage based on the average 3500 QC 4x4 truck. For your best mileage drive smooth and when on the highway keep the rpms between 2000 and 2100, that is the sweet spot for a 24 valve.

 

[MrFixit]

MPG

My numbers are like Vaughns. 23. 5 MPG consistent highway if I keep it under 70 and 18 MPG in the city. As most others say, it is mostly in the foot and the rear end ratio. Issue 33 did a story on all the specs for the Cummins and had some graphs at where the "Minimum Brake Speed Horse Power" (I believe this is what it is called) gave the Highest MPG and the #'s for the 2001 HO are at 2000 RPM. This is 70 mph on my rig. I have been getting these high MPG's by sticking to the 2000 rpm. THe issue lists other motors as well. Does not seem to make much difference between 60 and 70 mph but after 70 is where the MPG drops.

 

[Joe Mc]

Ironic - I was just going to post "Losey MPG"

I've read all of this post. Check my sig and note that I now have 90,500 mi. The bed is covered so drag shouldn't be an issue. I bought in June 01 was getting 21. 5 @ 60 - 65 hwy and 16 - 17 in town regullarly. On a trip to yellowstone I got an average of 18. 5 round trip while mostly traveling @ 75 - 85 on the hwy! Of course w/the occasional blast to 95 - 100 (3. 54 diffs). So I was happy till the dreaded winter blend kicked me down to a very regular 13. 5 to 14. 5 +/- depending on r/foot:{ I'm bummin big time. Any ideas? I don't run any additives and change oil & fuel filters regularly. Still have stock air box & filter - snorkel & silencer got lost about 1 week after I became a TDR member - can't imagine what happened to them . . . I think they were on when I brought it home('').



However, it still beats my last set of wheels and rides a whole lot smoother too. It was an 88 Toyota, 4 runner, V-6 FI 3. 0, auto 135K+. It got a best of 16 on the hwy and worst of 12. 4 round town in the winter. It wasn't much better in the summer. No oversize tires either.



Hope it returns to normal soon - Spring maybe. Share your thoughts - PLEASE

 

[CTabor]

I had a 96 3500 2wheel drive it got about 16 mixed driving 19 was its best ever on the hiway. My 2001 got about 16. 5 mixed driving untill I put on the 285's now it gets about 14 mixed driving on the hiway about 18. 5 was the best ever before the tires about 16 now. I have checked air to air cooler boots no leaks checked iat sensor it was clean did not check its voltage though my need to do that.

 

[DMalone]

I was getting 23. 9mpg at 70mph but when i went to 285,s i noticed that i now run boost almost all the time and of course it depends how fast i am running. I now get 17. 8 and we dont have winter fuel here. My tires are mud,snow heavy tread. These tires i have on now are a heavy tire, and i wasnt running before any boost until i hit a hill or passing etc. Just how my truck acts. But i do get alot better mileage in the summer.