Update on 98 fuel mileage HELP!!!!

[Archive]

well I am at almost at 1/4 of a tank and my mileage is at 240. 6 I CANT BELIEVE IT!! It seems to have gotten worse. I need some more suggestions PLEASE!!! My pump was looked at and my pressure valve was replaced and my timing was bumped to 14. 5 but to no avail on my 98 automatic 4x4. I did notice when I idle now I seem to get more raw fuel coming out of the exhaust than before. Would like to keep the truck but I need to straighten this problem out. Truck runs alot better with torque plate in and no cat. My egt is normal and my boost is normal so what gives?? I do hear a slight hissing sound when I shut the truck off but it lasts for 2-3 seconds then stops. I also just filled up on Sunoco premium for the first time instead of Texaco but that didnt help either. Remember I do alot of stop and go city driving(big city-- red light to red light not the city driving most of you guys are used too) No towing either. Please Help-THANKS

 

[Archive]

I think RedNut and I are in the same boat. I've got a '98 2500 12 Valve Auto, and I'm consistently getting 15 MPG.

Here are my driving conditions (Monday - Friday. ) 15 miles to/from work, average time to cover distance = 40 minutes. This route is full of up and downhill sections on I-405 between Renton & Bellevue.

I have not weighed my truck yet, but I do have a fiberglass canopy and about 50 lbs of tools in the bed. I guess I should take a LONG trip with it to see what kind of mileage I can get outside of the city. It would be nice to get better mileage... ...



------------------
Scott Collins
'98 Ram 2500 4x4 12 Valve Cummins.
Renton, WA

 

[Archive]

My expereance with city-highway driving,I drove approx 5-7 miles in stop and go driving in Las Vegas and I was getting 14-16 mpg,more city then highway. I am now home in Texas and live in the country 18-23 miles to the nearest big city 50 miles to Austin Tx,and I now get 18-20 highway-city mileage, are you sure that your timing is correct?and are you running in 4-wheel all the time? I used to get the hissing sound you described but it stopped after the timing was reset,to what I do not know,Chapmans Dodge did it. Have you checked your brake linings to see if they are constently draging,that will cause you to use more fuel,is your throthel and valves ajusted correctly?,are you leaking fuel at all when your runing done the road? When your at a 1/4 tank and refill how much fuel does it take? could your fuel guage be out of cali?, have you checked to see if what your fuel looks like,if it looks like good diesel? When you had your timing set did the dealer do it or a cummings dealer?,I would not have a Dodge dealer set timing unless I was absolutly sure they were as good as a Cummins mech. Dont know if this helps but might give some ideas.

 

[Archive]

Rednut. I'd pull off all mods (plate etc. ) except the cat,and return the truck to stock, unless you could find the problem easily from something else. Verify that your odometer is correct.
Take it out for a 50 mile ride on the PA pike,verify that it's within at least 10%.
I think you said you have 305's on your truck? Did you re calibrate for that?
Is your front end alignment good? Checking the brakes is a good idea, like Bill said.
I'd jack up the whole truck, and check each wheel to be sure they're rotating freely.
Do you carry a bunch of c**p in the bed?
Does your trans seem like it slips? Is it locking up?
I doubt that any one of these things will kill your mileage, but a few combined might.
HTH
Where is this "hissing" coming from?
I'm at 250ish mile mark on this tank, and it's down to one line below full?? #ad

I know it's not accurate!
Raw fuel at idle is no good. Is your return line blocked?
------------------
98 Quad cab 4X4 2500 12 valve,5 speed,3. 54 rears, 8' bed. Boost and egt gauges but basicly stock except for a "properly adjusted" AFC. Cat in the garage. Uniden HR 2510, Texas Star 1200 amp. 59,000 Mi as of 10/21/00.
NRA life member. High power/IDPA.



[This message has been edited by The patriot (edited 11-12-2000). ]

 

[Archive]

RedNut:

I wonder if your sending unit is accurate? What your fuel gauge tells you is less important than how many gallons of fuel you're putting in the tank per miles traveled.

My truck is driven a lot in the city of Atlanta during the week; this is all stop and go traffic, plenty of hills, and lots of idling at stop lights. Also, lots of short trips to run errands, etc. About once a month I take the truck on a long trip of about 600-800 miles (one way) and during these trips I flog this puppy -- trying to do 80 or so when I can safely manage it (monitoring CB and radar detector).

My city mileage is about 11-13. My highway mileage is never much better than 17. One time I got over 20 mpg, but that happened on a long leg of a trip from Rock Springs, Wyoming to Salt Lake City. The first 200 or so miles are down hill! #ad


I know exactly what this truck will do if I baby it. I figure I can take off a bunch of the crap I've hung on it, remove the tool box (with 600-800 pounds of tools), go back to the stock tires/wheels, drive like an 80-year-old church lady, and I'd probably get -- on the highway -- closer to 20 mpg. But, that'd be no fun! I knew that the 4x4 was going to hurt my mileage -- so was the automatic. I knew the tall/heavy tires, winch, bug-deflector, lights, brush-guard, tool box, etc. , etc. , would also exact a mileage penalty.

The problem is, I think, that we hear these stories about guys running stock, regular cab, short-box, 5-speed trucks across Kansas and bragging about their trucks getting eleven hundred and seventy six miles per gallon. My reaction is, "Yeah, you're getting excellent fuel mileage but I wouldn't want to swap -- and own/drive your truck -- if you gave it to me!!" #ad
If I want to brag about my fuel mileage, I'll do it up right, and buy a Volkswagen (diesel)! Then I'll get really seriously good mileage (but hate my ride); meanwhile, I'm going to drive around in a fuel hog that gives me a "woody" every time I get behind the wheel...

There's no mystery to getting great mileage: Reduce weight, reduce drag, reduce boost, reduce hills, reduce speed, REDUCE FUN!!!!

I've gotten really pragmatic about this. I figure I'm giving up about 3 mpg, consistently, to the guys in the "skim milk" trucks who live in Kansas and drive like Janet Reno on Valium. I'm averaging about 25,000 miles per year, and that 3 mpg amounts to an additional, say, 15% premium in fuel costs I have to pay because I like my truck to go fast and turn heads. 25,000 miles divided by 15 mpg is 1666 gallons @ $1. 50 = $2499 per year. Say I was averaging 18 mpg (damned few of these guys are -- truth be known... ) That's 1388 gallons @ $1. 50 = $2082

So, it's costing me (maybe) $400 more to drive FAST! in a heavy 4x4 -- with lots of goodies on it -- vis. a stripped down, nothing of a truck... My philosophy is that the money is well spent! This truck is (for lots of us) one of our most important sources of recreation, relaxation and pride. Wish I could help you with a specific solution to your problem.

I wonder if the "hissing" noise that you're hearing at shut down is your turbo spooling down. (Don't mean to insult your intelligence!)

Good luck troubleshooting your problem... #ad


------------------
97 2500 4x4, club cab, auto, 3. 54 limited slip, JRE 4" exhaust, Dr. Performance Fuel system (370 HP), "Twister Turbo," Geno's guages -- Boost, EGT, transmission & Rear -- MAG Hytec covers, SunCoast Converter/Transgo shift kit, Brite Box, tons o'chrome under hood, Prime Loc, EZ Drain, Seat covers, wood dash, Rancho Suspension, Warn M12000 Winch on Warn Brush Guard, Warn driving and fog lights, Hella twin back up lights, 285/75/R16 B. F. G. ATs on Mickey Thompson "Classic" rims; Linex bed liner, BD exhaust brake, Optima, "Red-top" batteries. Northwest Custom mudflaps, front/rear, and stainless rocker panels.

 

[Archive]

Sasquatch, I understand everything your saying. I know how heavy my truck is and I also understand that I cant get 20 mpg driving in the city, I was just curious if I could get a little more out of it than I am getting. At fillup I am putting in about 31 gallons everytime. It never bothered me before(mpg) but after joining this site I thought my truck was running ****ty compared to others. If that hissing sound is my turbo spooling down after shutoff then you are not insulting my intelligence, just answering a question that I didnt have the answer too Thanks

 

[Archive]

Raw fuel out the exhaust? I don't understand what causes this malfunction? Would like to know what causes that so I can keep my eye out for that. My current milage empty is 15 to 17 mpg, loaded 11 to 12 mpg.

------------------
Stephen's 1995 Dodge Cumming Automatic 3500 in Sanger CA. Pulling 35 Foot 9600 lbs 5th wheel. BD fuel plate 230HP,Air Filter Boot Removed, Gutted Cat, Vibrating Mirrors, Sreaming Tubro

 

[Archive]

RedNut,
You may have gotten the "winterized" diesel fuel. Your mileage will go down 2-3 MPG roughly. I noticed it too.

You are probably "getting" on the truck more than you used too. This does not help mileage either. Cold weather always = less mileage.

Raw Fuel: I know what you are talking about.

If you have an AFC spring kit installed. Back out the hex head screw at the back of the AFC housing maybe a full turn. I noticed my truck was running "rich" or "fat" at idle too. The exhaust would make your eyes water. A simple adjustment of the setscrew, or back off the star wheel(towards the front of the engine) should clean it up. Low end torque was not effected.




[This message has been edited by HEMI®Dart (edited 11-12-2000). ]

 

[Archive]

Let me clear up what I mean by raw fuel- I mean when I stand back by the exhaust after idle for a few minutes the fuel smell is REAL Strong. Before it was never that bad > I owned diesel before and know you get that smell but this is especially strong. Dont know if it because of the torque plate. THANKS

 

[Archive]

RedNut,

Try the adjustments on the AFC set screw to clean up the exhaust at idle. I was having the same problem. Do your eyes water from the exhaust? #ad
The torque plate only comes in to play at mid & full throttle. The High performance torque plate shouldn`t have any effect on engine idle.

[This message has been edited by HEMI®Dart (edited 11-12-2000). ]

 

[Archive]

Rednut,have you tried pulling the handle down on the left that says brake release? #ad

 

[Archive]

I guess all I can do is join your 'party'. Mine's a '98 12V 5spd, 3. 54 LSD, long bed quad. 265s for tires. Essentially stock except for an Amsoil air filter. Mostly drive it around town, to and from work and errands. I'm getting 15 +/- pretty consistently.

I bought it this summer with 45K on the odometer from a gal who used it as her daily drive. Never towed anything, never hauled much. The guys at Cummins said it was not broke in yet. At their suggestion I hooked up my friends tool trailer (about 5-6K lbs) and towed it 300-400 miles out on I-84 over a couple of weekends. Wrang the crap out of it going up hills. So far, no change in mileage. I'm still trying and checking things though.

Love the truck, but everyone had me expecting more before I bought it.

JGK

 

[Archive]

RedNut,

Another thought...

It's possible that you are leaking fuel from a tank fitting or line. I know that sounds dumber than a bag of hammers, but it's possible.

If you are smelling "raw fuel," that distinctive, very strong smell of diesel, by the rear of the truck, I think there is a chance you simply have an undetected leak in your fuel system.

I would consider checking all the connections between the filler neck, tank, fuel lines (leading from tank), and the area around the top of the tank where the sending unit is fastened in and sealed. I don't think that unburned fuel (when it exits the exhaust) smells strongly of diesel. I think the clouds of black, soot-filled smoke we see in our rear view mirrors when we're over-fueling our trucks are simply evidence of improperly combusted fuel -- not truly "unburned," in the sense of liquid diesel fuel. I don't think diesel (in its fresh-from-the-pump state) ever drips out of our exhaust pipes. That just can't happen. Fuel that is injected into cylinders at high pressure, then compressed, then subjected to 900 degree temperatures (or, whatever... ) isn't going to come out the exhaust end of our trucks smelling like diesel fuel -- at least I'd be totally stunned if it could...

I could be completely wrong about this, but if there is a very strong "raw fuel" smell at the back of your truck -- and your mileage is ridiculously bad -- I'd suspect something completely "unsexy" like a simple fuel leak at, or around, the tank itself...

I've had trucks (several of 'em) leak at tank connections/ fittings several times over the course of my vehicle ownership history. Filler neck to tank connections are notorious for this. Sometimes such leaks can be very difficult to detect, too, because there won't necessarily be evidence of spotting on the ground -- even diesel evaporates pretty quickly; sometimes the tank will only leak when it's very full, or when the truck corners, sharply, to the right (sloshing fuel toward the filler neck), or when you brake while stopping (forcing the fuel to flow forward and pressurize the top of the tank)...

I have, at one time or another, done everything (stupid) conceivable to make my truck go faster (messing with timing, pump, spinning "star wheel" to the max, trying different injectors... ) and I've never, ever smelled a strong, raw fuel odor at the rear of the truck...

I hope it's something really simple like a loose filler neck attachment. Good luck.

 

[Archive]

JGK,

You make a valid point about unrealistic expectations, vis a vis fuel mileage. This has been a pet peeve of mine, too, for the past couple of years. My truck was represented to me (at time of purchase) by my salesman as being "more costly up-front, but more economical in the long run. "

"Sure you'll spend a couple of bucks more, now, but you'll have a virtually maintenance free truck that'll be MUCH more fuel efficient!" The reality is, with fuel in our area now anywhere from 35-45¢ per gallon higher than regular unleaded, our trucks are MUCH MORE COSTLY to operate than a guy driving a gas burner.

My '92, 3/4 ton, Ford (spit, hack, cough) E-350 van, fully loaded with tools, lumber, and ladders on top got about 8 mpg around town. Ditto my other work trucks, including two GMC one ton dump trucks. They'd all get 7-8 mpg, no matter how they were driven. Regular fuel can still be bought in our area for about $1. 24. My last fuel-up at the closest (to my home) station cost me 169. 9 per gallon for diesel fuel. So, that's a 50¢ premium I'm paying, right there. Forecasters are predicting a relatively mild winter (in our area) but the nation's stores of heating oil are low, and the resulting demand/price-pressures will keep the cost of #2 diesel at these levels, or even drive them higher. By contrast, seasonal demand for regular gas is tapering off, and prices are dropping.

If I'm paying 30% more for #2 diesel, and getting 30% higher mileage (dubious, anyway... ) then it's a wash -- purely on the fuel-economy front. But, remember, these trucks are WAY MORE expensive (purchase price) and I'd argue that they are more expensive to maintain, too -- not less. About a quarter of the Dodge dealerships around here simply refuse to work on the Cummins -- don't even have diesel mechanics in their service departments. My nearest dealer (city of 4 million) that caters to Cummins owners is a half hour's drive (in light traffic) away from my home.

I read the wild stories (exaggerated efficiency feats... ) about the fuel stinginess of these trucks before I bought mine (in the TDR), but noted that the editors were always VERY CAREFUL to discount some of the more outlandish claims.

People are proud of their trucks and want to talk them up, any way they can. It's human nature to want to boast about our pride'n'joys. The bottom-line reality of this fact is that many owners simply overstate the mileage their trucks get -- it's not "fibbing," really -- it's more like "wishful thinking. "

I came, early on, to the conclusion that a four ton truck simply isn't going to be fuel efficient -- not by any reasonable measure -- when driven, daily, from grocery store to shopping mall in stop'n'go city traffic. It isn't going to happen...

My best guess about these trucks (particularly the TDR "pool" of "bombed" trucks) is that they average about 12 mpg in urban settings; they get about 15-16 in "mixed" city/suburban driving, and they get high teens or very low 20s in exclusively rural settings. Average the averages, then, and you've got a truck that gets, maybe, 15 mpg most of the time. Figuring $1. 70 (and going higher) fuel costs -- a lot of people are going to want to cut back on superfluous, Sunday sightseeing in their favorite RAM. #ad


Again, (for those who truly obsess about fuel efficiency... ) maybe it's time to look for a used VW diesel to use as a daily driver; then, just leave your Ram parked until it's time to hook up the 5th wheel.

 

[Archive]

Amen SasQ
I get an honest 48mpg mixed city/hwy with my 80 Rabbit diesel PU. I love it!

Think about it, thats serious milage #ad


------------------
1972 Chinook class C with 96/215 5spd, 4/5" exh, 4"BD, MagHytec, 85gal fuel, K&N RE0880, AutoMeter, 370's, BD gov kit, BD afc kit, yada-yada-yada
www.fostertruck.com/cummins

 

[Archive]

I have found that if I keep my tank at half and above that I get beter fuel mileage.
As fuel rises from the supply tank the vacuum has to increase as the tank gets lower as the vacuum increases the phenomenon of resistance to air-vapor flow becomes evident. As this phenomenon happens it causes entrained air that passes into the injection system that distortes the spray pattern of the injecter thus causes poor fuel mileage and performance.

------------------

 

[Archive]

Doug,there will only be a vacuum in your fuel tank if the little red cap on the tank vent hasn't been removed. Lack of removal has even caused some fuel tanks to collapse. The vent is on top of the tank module.

 

[Archive]

Sasq,

I hear ya. But you know, on the bright side, if and when the price ever gets down to what it used to be (at or below reg. unleaded) the price of our mileage will seem trivial by comparison and this issue will probably tend to fade away. But its gonna be a loooong winter.

JGK

 

[Archive]

Hey folks,
I climbed under my truck the other day when I read about the red cap on the vent line of the fuel tank. I actually have small hose connected to that connector which travels upward along side of the fuel delivery line. My truck is a 1996 3500 4x4 which I purchased about 5 weeks ago. Did they run a vent line on some of the older models, and cut the cost on newer ones by omitting this line? #ad




------------------
Mark
1996 Dodge 3500, 4x4, Green and silver.

 

[Archive]

I just bought a 97 2500 4x4 5 spd. with 3. 54. . driving it home from the purchase, I set the cruise at 70, with the a/c on ... i calculated 23. 54mpg, not including the over-tall tires... . actual is closer to 24mpg! This motor has a 230hp plate, stock air filter, and a 4 inch exhaust. Its economy is about the same as my old 95 with similar mods!... you guys must have *something* wrong!