Alright, this is driving me absolutely INSANE since about late last fall, my milage has dropped down. When I first got the truck last Sept. there were a few times when I have gotten 19mpg, and even hit 20 once. It went in the S****** about in late November. I was originally blaming it on winter diesel, but now the best I have gotten is high 15 on the last tank, 85% unloaded. It was mostly around 14 before the new air filter. Right now, I have less than 5/8 of a tank and I only have 140 miles out of it. 40 of them were pulling about 12-14K, 50 about 4-7K, and the rest unloaded.

Changes done to truck since I bought it:
AFC full forward in fall (slid it back to stock 3weeks ago)
Timing
Added 33" tires (from 245's)
Straight piped it last winter
plate was already forward a bit when I got it
Adjusted valves
New overflow valve
BHAF filter this spring
plugged wastegate activation line


What else is there? My cruising EGT's are around 700. I am starting to get a white haze on start up after sitting. Not really a cloud, but more of a haze. Could this be a dribbling injector? The only other thing I can think of would be the wastegate is hanging open? One of these days I am going to do the fuel prefilter screen, is this a fleetguard part?

Any ideas would be very greatly appreciated. I am driving like a grandma trying to squeeze the best milage I can out of it.

Thanks in advance

 

Since it seems you've covered everything pretty thoroughly my first bet would be the timing wasn't set correctly and isn't what you think it is. Quite common to get it wrong.
The wastegate is spring loaded, if it's hanging open it should be open all the time, you would have low power on acceleration.
The pre-heater screen can usually be serviced without any additional parts.
Directions here- http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

 

The wastegate is one thing that makes me curious. On my test drive with my BHAF, all was great, I came to a stop, then hammered it and left a HUGE cloud of dark grey and black smoke. I stopped 1/4 mile later and tried again, and nothing. I could never get it to do it again. Is there any way to manually close it for good?

 

If you have not re-set your proper tire diameter into the computer your fuel mileage is going to be out

 

I don't think the 94's had computers.
The tires are not good for milage. The larger the tire the worse off you'll be. More dead weight to move. Unsprung is an unseen problem with milage. It has to be moved and then constantally pushed. Real hard on the power.

When my truck was new I got 20 MPG, but now after all I've done it and 300K miles the best I can get is 17.8. And thats new injectors. The timing is set t 17* but the largest problem is the foot. Every time you push the petal more than it takes to move the truck, there goes the fuel. I really don't know what the answer is. I haven't found it yet. One of the boys that went to Muncie with us drove a truck up there, put on slicks, drag raced in the bracket, drove home and still got 23MPG. How? I don't have a clue. I towed my fifth wheel and got 11. It just ain't fair.

..Preston..

 

if your on the throttle with ctd you get 15-16 miles but with a hemi it would be 10-12 miles and 30 cents more a gallon.
I too have had fuel concerns and that is from the odometer check and gallons of fuel to fill up, computer on 96 doesn't cover fuel milage, but I do have 285 tires which I think has something to do with it I think I am getting more miles than whats showing up if my 245 would turn so many times for each mile and lets say the 285 turns 10 less times per mile after 300+ miles there would be differences. just my 2 cents

 

http://www.dakota-truck.net/TIRECALC/tirecalc.html

go there, use the tire A and tire B calculator to figure out how far off your speedo is reading if you've made no corrections for tire size

 

Boy that was handy. Just by using the calculator my mileage went from 12.6 to 15.5.....

I thought I was only off by 10%, turns out it was closer to 22%.

Thanks furious70!

 

Yes and no on the tire argument. I gained 2 mpg by jumping up from 245s to 315's both AT's and my speedo is always reset to dead nutz. My cruising RPMs on the highway are in the low side of thier optimal range instead of 300-400 rpms higher at the top end of the torque curve, all at the same speed mades a considerable difference for me plus when pulling a grade with a trailer i can hold direct to a higher mph than before.

Just the flip side of that argument.

Otherwise check for a bad fuel line betweent the lift pump and injector pump letting a little air in and definately check timing sounds like white smoke ussually is the tell tale there.

 

Crimedog:

Your signature also says your TC is slipping. How much and how bad? Maybe your burning that up more than you realize. Sounds like time for another upgrade Just another thought.

Paul

 

i used my gps to check out my speedo, it was dead on at 60 mph with 235s on my dually. but then i checked out my odometer, it is off 3.5% as in it reads 3.5 miles low for every hundred miles traveled. you can just use the mile markers when you are on a trip. i checked mine with a 10 mile trip then a 100 mile trip, right at 3.5% off. and it sounds like your timing has slipped, that would be the first thing i would check. mike

 

in my truck new fuel filter gets less milage 14.5 old gets 17.5 did you change your fuel filter durring that time ?

 

Fuel Filter has about 3k on it, changed it twice since I got it. Paul, I am thinking the TC might have a bit to do with it, because the milage started slipping about the same time the TC started slipping. When I get up to speed, if I'm nice my EGTs are about 500 then the TC locks in, they go up to 800 and then come back down. RPMs also drop from about 500 or so. I am going to try the GPS to test the spedo. I have been factoring in the difference in my milage. Timing is going to be done on July 10 at the bomb party.

The white haze is really playing with me. The last couple of days, it has been about 50 degrees when i startup in the morning. let the grids cycle, start, NO SMOKE OR HAZE whatsoever. The days I get haze is when it is around 65 or so, no grids, seems like just not enough heat. I suppose that'd be timing

Thanks for the input, guys. I am hoping that between timing and getting that GB tranny one of these days I can get it back up. (Only got 1100 left to save up for the tranny )