Loss in fuel mileage

[RHanson]

Help... I have a loss in mileage. Engine sounds and runs good. But ive gone from 24mpg empty to 14mpg. In tow from 17mpg to 10mpg. Ive had the injectors gone through and the valves set but still no difference. 95 2500 180hp. 160,000miles

 

[Cummins Corvette]

I think you just finally figured out how to use a calculator. Seriously, I only get 15-16 out of mine, mostly highway. 18 of so hwy only. Check for leaks in your intake, change your fuel filter and air filter all the usual stuff. Maby you got some bad fuel. The real pros know some tricks that I don't though. Good luck. BTW the best towing milage I have gotten is 10 w/ a 21' TT.

 

[illflem]

You may be losing boost somewhere, check the intake tube clamps and manifold bolts for tightness. Plugged fuel or air filter filter can also lower your mpgs. I consistently get 22-24 mpg with my 2500 empty.

 

[Breck]

Possibly the CAT plugged up?

 

[grtescpa]

Originally posted by RHanson

Help... I have a loss in mileage. Engine sounds and runs good. But ive gone from 24mpg empty to 14mpg. In tow from 17mpg to 10mpg. Ive had the injectors gone through and the valves set but still no difference. 95 2500 180hp. 160,000miles

Have you gone to larger size tires? Larger tire diameter means the axle speed will be slower and more road friction. The best way to check fuel consumption is by hours not miles. Install a good Hobb's meter and go by that.

 

[Steve Campbell]

Do the 12 valve engines have MAP and IAT sensors and if so they could be faulty???