So, Im liking the new 12v I just picked up, but with the 20+/- gal tank, I noticed Im fillin up alot more often than the excursion with its 44 gallon tank. What mpg should this truck be getting? Its got the pulling 4:10(or thereabouts) gears in it, and I rarely drive it over 70. Is there an easy culprit to diagnose the 13mpg's. I know it should be better than that empty. So far, its only got cold air in and 5" straight air out. Hell, Im a little fearful of modding it at 13mpg's stock! Any tips would be greatly apprieciated

 

i have a single cab 12v and it only gets bout 16

 

Well my truck has 4:10 gears in it and i was getting about 18-20 before my converter took a dump. Iam not really sure how duallys are as far as mpg but here are some things to check on. Air filter clean, make sure torque converter is locking up, overdrive is working fine. Also take into consideration that it is winter time and you'll see some lost mpg, in the summer time it should improve.

 

In the winter, depending upon where you are climate-wise, the refiners add number 1 to the diesel (number 2), and the #1 has less BTU per unit then the #2, so miles per gallon go down. But, the best way to increase mpg is with a light foot. No need to stomp on it, and no need to race from traffic light to traffic light.

 

those 410 gears are rough on fuel mileage as well as a heavy right foot

 

id also check boost boost leaks because they will lower your mpg also.

 

It's not #1 fuel winter grade fuel is #3. #1 is heavy fuel oil.

 

I'd take a look under the truck, while it's idling and check for any spraying fuel, under the engine. Fuel line return is notorious to weather crack. A dirty air filter will also take a bite. Also, could be that someone has already messed with it, messing up the fuel consumption.

It's a 4x4? Does it have huge, after-market tires? Just noting that going to bigger tires will give false readings. Odometer will roll slower and Speedometer will show slower, so you'll be going faster than it's reading and getting better mileage than the odometer shows.

20 Gallon tank? I thought all 2nd generations had a 35 gallon fuel tank as a standard. At least, that's what my manual shows. They sure set the fuel gauge conservatively on them though. When my needle is on E, it usually fills up with 29 gallons. 6 gallons of reserve!

I can get about 480-500 miles per fill up, which is usually 28-30 gallons, according to the pump. About half for stop and go traffic and the other half, freeway driving @ 60-70mph. I don't know the gear ratio, if I were to guess I'd say high 3's or maybe low 4's. It's an untouched '94 with 75k, though.

 

I have a 35 gallon tank in my 12V.. mine is 4x4, has oversize aftermarket tires AND 4:10 gears - over the road I got about 23 MPG after installin the airdog and a couple of other mods I have.. in town, I was still gettin around 18mpg... Low stall converter helped too I suppose.

 

I know mine starts really sucking fuel once I go over 2000 RPM on the freeway..