some help/advise...
 

I just got a 94 3500 quad cab a week ago. And from the first tank of diesel. I am only getting 11.8MPG. Is this normal? Also noticed when i am on the highway and cruise set at 70, im running 2600-2700 rpms..I was wondering how i can get more MPG? Thanks..

How old are injectors? is the lp working properly? these play a small part in fuel milage also what gear ratio do you have ?? in the glove box there are codes as to what gear is under the truck GT4=3.73,GT5=4.10,GU6=3.42 also tire size will matter

[ATTACH][/ATTACH]Not sure how old the injectors are. The guy i bought it from said they were replaced by the previous owner. Not sure what you are referring to LP? I have 4:10 and i currently have 215/85-16 tires on it..I just put in a aftermarket air intake, and relocated the PMD.

LP= lift pump and that hot air intake you have does not help your fuel milage loose it aan get cooler denser air from outside the truck this will greatly improve the fuel milage also leaky injectors will cause poor milage and with 4.10 gears you will turn higher RPM's I stay at 65 MPH anything over that I loose 2-3 mpg easy

Ok how can i tell if the Lift pump is working properly? And how would i go about getting cooler air from the outside? Is there a way to check for leaky injectors? Sorry if they seem like dumb questions, but this is my first diesel and trying to get it ready to hit the road towing and hauling..Thanks for your input.

do you have white smoke upon startup??this would indicate leaking injectors and find a stock breather box either the original type that came on a 1994 or a later K47 style that uses the cone filter would be better than what you have on the truck now

Best bet is to run lower rpm, I know it can be frustrating, but it seems like for me as soon as I start getting over 2000 rpm, mileage is straight down hill from there. I got 3.73 so its at about 65 mph so not so bad for me.

To increase mileage I would say exhaust and intake, maybe injectors if they are bad, but not really much more to do.

No i dont have white smoke at start up. I am going to build a box to go around the cone i currently have on it. I already have a what looks like 3" coming down from the headers in to 4". Would you recommend going 4" all the way?

So white smoke on start up is leaking injectors, I guess mine needs new injectors.:dang:

As to MidwestWelder, a 3" down pipe and 4" the rest is plenty for these engines. With 4.10s and a 1 ton, and I assume an automatic and 4x4, you can never really expect too great of mileage, especially with the older automatics since, in my opinion, they are terrible. Even though you should be gettin 15 or so going 70 like ya said, unless its a dually, then around 12-13 is more correct.