Poor mileage need advice

[dbartos]

Hello, I just filled my tank for the 3rd time since buying my 95 RAm 3500 in August I checked my mileage and I am still only getting about 13. 5 Miles per gallon. I have not pulled or caried anything and all my driving has been on fairly level terain. (no mountains or steep hills) I'm a little disapointed in this mileage and looking for advice on how to improve it. I just replaced the air filter so maybe that will help some. How can I tell if my turbo charger is working corectly. Since this is my first diesel I don't know to much. I'm not interested in doing any extensive modifications but would like to improve the mileage. I understand that some people are getting around 18 MPG and that would make me real happy. Any sugestions? DB

 

[Joe G.]

If you don't have a boost gauge it's hard to tell if the boost is what it should be.



One thing you can do is check the boots on the intercooler pipes to see if there are any leaks. Some people have had the one on the bottom of the pipe on the driver's side get a hole rubbed in it. Also make sure all the clamps on the boots and pipes are tight.



You might adjust the valves. Probably won't help, but it might. Can't hurt.



Retarded timing can cause poor milage. Checking or changing the timing requires special tools.

 

[Got Smoke?]

I gained about 1. 5mpg (foot removed style driving :{ ) when I bumped my timing. We checked what mine was at and it had slipped all the way down to between 10 and 11 Degrees!



One thing I haven't seen mentioned is what gear ratio do you have? If you have 4. 10's your mileage won't be as good as someone who has 3. 55's (like me)



Mine is not modified extensively as you can see in my sig. but IF I can keep my foot out of it I see 18. 5MPG at the pump without correction for my oversize tires.



One last thought you mentioned that you changed the air filter, have you changed the fuel filter yet? $14 from www.Genosgarage.com and its only a 20 minute job (the first time )

 

[illflem]

Have you checked against highway mile markers to insure your odo is correct? If your tires aren't stock size your numbers could be way off. Besides what the others have said a clogged fuel filter can also bring your economy down.

 

[dbartos]

The odometer is accurate. According to the sticker on the hood it has a 3. 55 rear end. I will check the intercooler hoses and clamps. Thanks for the advise.

 

[dbartos]

By the way RPM is exactly 2000 at 65 Miles per hour. Does this sound right for a 3. 55?

 

[Got Smoke?]

Originally posted by dbartos

By the way RPM is exactly 2000 at 65 Miles per hour. Does this sound right for a 3. 55?

Sounds about right if you have factory size tires I believe. I have 33" tires and I turn 2K RPM at 70mph.

 

[AlK]

Also make sure that the tires are properly inflated.

---

Al

 

[Texas Diesel]

You may be getting winterized diesel in the mid west by now. MPG is slightly lower on that stuff.

 

[chucksram]

dbartos,

I have a 3500 with 3. 54 gears and at 2000 I am doing 75 mph.

It sounds like you have 4. 10 gears.

Mine is an auto trans.

Chuck

 

[WadePatton]

Tire size would account for the speed/rpm difference. Stock tires can be 245 or 265. I don't think that is the problem.



May as well put boost and EGT guages on it. You'll love 'em.



Can you hear the turbo spin down after shutting it off? That would assure you that it's turning freely. Fuel filter and boost leaks are where I'd be looking.



I'm sure there's a way to pressurize the intake with the motor off and listen for leaks--like radiator testing.



good luck--you've come to the right place.

 

[daveshoe]

How long are your trips?

Short trip driving does not equal good mileage. My 02 HO gets around 15. 0 average with 5 stop signs in 15 miles, a short trip for dinner & material runs. Truck weighs 9700 most days . First tank went 17. 2 but truck weighed 2000 lb less and was more aerodynamic. I need to test it on a long run after 10000 mile break in.

 

[Jeremiah]

Re: How long are your trips?

Originally posted by daveshoe

Short trip driving does not equal good mileage. My 02 HO gets around 15. 0 average with 5 stop signs in 15 miles, a short trip for dinner & material runs. Truck weighs 9700 most days . First tank went 17. 2 but truck weighed 2000 lb less and was more aerodynamic. I need to test it on a long run after 10000 mile break in.

Shucks, I just took delivery on my '03 3500 SWR 6-spd HO and 400 miles into the first tank the computer average mpg has crept up from 14 mpg and has now stablilized at 20. 1 to 20. 6 driving in mixed driving but mostly in the mountains from 6,000' to 9,500'. I can't believe it's this good! I'm knocking on wood and keeping my fingers crossed! Yeah, yeah, I know ... break 'em in hard.

 

[Big_Daddy_T]

Wouldnt it smoke if it had air leaks? Those 12vers get awesome mileage. I have had a bug in mine since i put the pnp on it. my mileage went from 17/24 to 13 flat. I havent been able to recover it completely. I ditched the pnp for a comp and now i get about 15/17 depending on my foot. I think my new injection pump netted me an additional mpg. Because I have gone through almost everything in between I think its a bug in the computer. Its an awesome truck with mucho power so Im not worried about the mileage.

 

[Joe G.]

Have you tried a stronger throttle spring so it's harder to push?

 

[andrewkoperdak]

I weighed my truck on a 10K scale. I only weigh 6200 pounds... this will lend to my fuel milage of 19 city and 23 mpg calculated by hand. I have 3. 54 gear and a 5spd. I run 2000 RPM at 70MPH. My tires are 265/75/16. Your truckk is much heavier than mine. That and I am sure you are running smaller tires might account for your milage.

 

[Jeremiah]

Originally posted by AKoperdak

I weighed my truck on a 10K scale. I only weigh 6200 pounds... this will lend to my fuel milage of 19 city and 23 mpg calculated by hand. I have 3. 54 gear and a 5spd. I run 2000 RPM at 70MPH. My tires are 265/75/16. Your truckk is much heavier than mine. That and I am sure you are running smaller tires might account for your milage.

My SWR 3500 weighs 7880 w/me, my two dogs and 60 percent fuel on board. It has 3. 73 gearing and 17" wheels, and has 1,400 miles on the odometer (new truck). I get 18. 5 cruising up and down the pass to Colorado Springs. I leave Monday for a long trip and will see how it does on the highway.

 

[paccool]

Get the boost gauge first to make sure the turbo is working right. One thing I have not seen mentioned is the injectors. If they are clogged/dirty, they won't spray properly.



Sounds like you need to take the truck to someone that knows how to set them up the right way. Timing, pump setting, injectors all need to be right to get the power and mileage.



If I keep my foot out of the throttle, I get 20-21 with my old first gen. Usually around 19 tho cause I really like to feel the power !

 

[Jeremiah]

Originally posted by paccool

Get the boost gauge first to make sure the turbo is working right. One thing I have not seen mentioned is the injectors. If they are clogged/dirty, they won't spray properly.



Sounds like you need to take the truck to someone that knows how to set them up the right way. Timing, pump setting, injectors all need to be right to get the power and mileage.



If I keep my foot out of the throttle, I get 20-21 with my old first gen. Usually around 19 tho cause I really like to feel the power !

I think I am in this thread accidently. Somebody else was asking about poor mileage. It wasn't me.

 

[Houser]

Hi Mike From Alaska here.

I I have a fix for your mileage problem that will sound so simple you will probably be reluctant to try it. But her goes. You drive a

Dually so you got lots of tires on the ground. If all those tires are not inflated to same psi they work against each other and cause lots of drag. Inflate all your tires to the recommended psi. If they are E rated tires that will be 65+ psi. The ride will be hard bu your mileage should get better.



Mike.



02 Ho w/every thing and some engine mods to boot