Fuel economy bad

[Edd Wadsworth]

Recently purchased a 2004. 5 QC Ram 3500 SRW auto with 3. 73 gears. The fuel economy is not as expected. I got 20. 6 on 270 mile hiway trip at 65-70 - seems ok. City I've gotten 12. 0 and 13. 6 so far. Pulled my 35' 5th wheel for 185 miles and got 8. 7 running 62-65 mph. These seem real low. Don't know where to start looking.



Purchased from a widow who said her husband got over 20 on hiway and mid to high teens in city which seems consistent with what my friends are getting.



In March she put gas in the tank. When it wouldn't start, she took it to the Dodge dealer who drained the tank, put in new fuel filter and new injectors (R5135790AF). They did not replace the high pressure connectors (mileage 102K). I have recently installed a new lift pump - same as factory model.



The truck has 108K miles. A transmission flush was done at 83K. Truck seems to have no addons.



Any help would be appreciated.

 

[JJPage]

Your mileage, if hand calculated, seems about right. The around town/city may be a bit low, but the towing matches mine at around 9mpg, and the hiway is decent, I have never made 19mpg. The injector numbers you posted mean little to me, but one of our parts guys may be able to identify them as new or remans.

 

[Bob4x4]

The r signifies reman

 

[MChrist]

The high pressure pump wasn't replaced?? I would think that would be the first thing to take a dump after gasoline ran through it. Very tight tolerances, and it uses the lubricate of the diesel to keep it that way. Gasoline would wreak havoc on the parts.

That being said, if those numbers are hand calculated, they are in the ballpark.

 

[rscurtis]

The Rokktech crank sensor will help mileage on that truck. There was also a reflash for that vintage early in their life, I forget the number but it also improved FE considerably.

 

[Bob4x4]

Most trucks that have gas added that I see get a very high percentage of gas and do not run long enough to do any damage.
Over 20 mpg is great for a 325hp. Towing mileage has too many variables
I get between 13 and 17 towing my Airstream depending on how and where I am driving. Most trailers are much harder to pull than mine

 

[cerberusiam]

Were you towing with OD off when you got the 8. 7? At the speeds you were towing and guessing at the weight that should have been 10-11 mpg. However, weather, terrain, etc will make a differnece.

 

[Edd Wadsworth]

All mpg's are hand calculated. I towed in OD from Spokane to Ellensburg (WA). That's west and typically into the wind, but don't remember much wind that day. I believe my 5th weights 14K.
On the gas problem, I remember her saying the gas/diesel was about 50/50.

 

[JJPage]

Edd, my 5ver weighs about the same as yours, and I've ran the same route as you did many times. You pulled Vantage twice, got to tell you, I think your mileage is normal, or at least it's as good or better than my truck.

Just a suggestion, you may want to go into the "user control panel" and "edit signature", it will help the rest of the members in their ability to assist you.

Jess

 

[cerberusiam]

Thats pretty flat ground to be getting that low of mileage, especially at those speeds. If you were doing 75+ I would say slow down but at 62-65 with stock tires that should have been in the sweet spot.

Based on the experience with my truck, 10-11 would be the norm stock, 11-12 with some added power and timing. Maybe trailer catches more wind or something like that but it does sound low.

 

[Prairie Dog]

All mpg's are hand calculated. I towed in OD from Spokane to Ellensburg (WA). That's west and typically into the wind, but don't remember much wind that day. I believe my 5th weights 14K.
On the gas problem, I remember her saying the gas/diesel was about 50/50.

That can be a brutally hard run. I remember coming across there heading west into the wind last time and seeing my boost and pyro gauges reading the same as they did when climbing Snoqualmie pass. So your mileage doesn't sound bad. Now if your going the opposite way I would expect mileage to be closer to 10~11.

 

[gerry]

I've also got a 2004. 5 3. 73 but dually 4x4 auto and I have never got over 14 highway (usually11-12) empty, 11 around town and 9. 5-11 pulling our 8k bumper pull toy hauler @ 65. All hand calculated. I should add that my Smarty jr is set on level 2 for both. My 2001 2500 4x4 with the same equipment got 14-16 around town, 17 highway and 9-10 pulling our toy hauler. I don't have a clue how some get over 20 empty and 14 and up towing but I don't.

 

[Bob4x4]

I've also got a 2004. 5 3. 73 but dually 4x4 auto and I have never got over 14 highway (usually11-12) empty, 11 around town and 9. 5-11 pulling our 8k bumper pull toy hauler @ 65. All hand calculated. I should add that my Smarty jr is set on level 2 for both. My 2001 2500 4x4 with the same equipment got 14-16 around town, 17 highway and 9-10 pulling our toy hauler. I don't have a clue how some get over 20 empty and 14 and up towing but I don't.

Most people don't... ... ... ...

 

[S.Morris]

I recently made a 900mile trip with my sig truck. It was the only trip I have ever made with it that I was not towing or had a bed load that did not allow use of my tonneau cover. I ran a hand calculated 18. 5 USMPG and was carrying about 1500lbs. Cruise set at 68mph.



Towing my 37' 5th wheel I see 10. 5-11. 5 on Florida trips, usually with nasty headwinds. This at 62-65mph.



Ironically this truck does very well in rural/city type driving empty if driven conservatively, giving a consistant 17 in summer weather. I think it does much better than auto trucks in this type of driving but, can become cumbersome in too much city with the NV5600 empty.

 

[DaveHess]

I'm with Gerry. I tow gross combined of 17,500 with my Jayco TT and am real lucky to get 11 mpg at 69 mph. I use 69 mph as that puts the engine at right around 2000 rpm. Most of the time I am at high 9's. I just filled up last night with #2 and hand calculated my mileage at 11. 36. Thats a bit low for around town unloaded for me. Normal would be around 13. Not sure why the drop. It did take me 41 days to use 25 gallons however .

 

[cerberusiam]

Thats a bit low for around town unloaded for me. Not sure why the drop.

That is easy to explain. When the only thing between you and north pole is a bard wire fence its gonna effect mpg. :-laf

 

[Prairie Dog]

Unloaded around town I get 15~16. Used to get 17~19 before stupid ULSD.

 

[rscurtis]

Last trip from St. Thomas to Coolspring PA and back was 22. 68 MPG (hand calculated) at an average speed of 48. 6 MPH. It consisted of an equal amount of two-lane roads and time on I80. It also included three climbs to 2000+ feet of elevation. The tank before that for local driving was 16. 9 MPG, it should have been a little more but the pump stopped at $125 on the previous fill. It probably would have taken another gallon or two.

 

[AH64ID]

The trailer mileage does seem a bit low, but I have never towed on stock programming and it's not setup for the best economy. Towing on relatively flat ground (only gaining 1,000 feet in 200 miles and nothing more than 5% for . 75 miles) I get 9. 5-10. 5 with a head wind and 10-11. 5 without one. That's with my sig truck and trailer, 17. 5K without the 4wheeler and 18K with it.

Here are all my fuel ups.

-

 

[HBarlow]

Unfortunately many Dodge-Cummins owners spend a lot of time worrying about a problem with their truck because their fuel mileage is not as good as some bullship artist claimed his was. Most but not all men "exaggerate" their fuel mileage claims.

A truck with 3. 73 gears pulling a 14k fifthwheel trailer westbound in overdrive at 62-65 mph with the huge frontal area fithwheels present to the wind was doing okay to get 8. 7 mpg. It might do slightly better if you lock out overdrive using the Tow/Haul mode and let it run in third direct at around 62 mph.

Joe Donnelly has written, if I remember correctly, that the most fuel efficient engine rpm for the HPCR 5. 9 engines is around 2000 - 2100 rpm.