A question about fuel mileage in my 85 Ford F250 with the 6.9 IH diesel engine. In my estimation, the mileage stinks, kind of dissappointing. I've got four other diesel trucks, and that's what I'm comparing it to. This truck is the heavy F250 with the 8600 lbs. GVRW. Four wheel drive, and three speed automatic with 3.55 gears. Tach shows around 2500 r.p.m. at 55 m.p.h. It only has 60,000 original miles on it, and it starts and runs like a clock. In fact, comparing it to all my other diesels - which are Chevys, this one starts the best. But, so far, in winter driving and never any faster than 60 m.p.h. yet, I've gotten 10 - 11 m.p.g. Truck had some weight in it, but I wan't pulling anything. Same situation, my 6.2 Suburban with three speed automatic and 350 gears would get 17-18 m.p.g. My 1/2 ton Chevy pickup with 6.2 would get 19 m.p.g.
Anyone else experienced this kind of mileage? And again, truck runs perfect, no sign of excessvie exhaust smoke, etc. I was expecting 14-15 m.p.h., not 11. Maybe better when warm weather and summer fuel comes?

 

well summer fuel will surly help out.but the ford factory intake and exhaust is very restictive on these trucks.with only 60,000 i will guess that it is factory stuff on your truck.cut the soup bowl out of the air cleaner cover and put a 3 inch exhaust on it and your fuel milage should go up.i am not to familiar with the 6.9s but my 7.3 has the banks power pak on it and i get 18 -20 mpg in the summer.even got 22 mpg once!

 

Believe it or not most MPG problems have more to do with faulty calculations and wind resistance than any thing else. I have discovered when it comes to miles per galllon figures the first liar doesn't stand a chance. If your Diesel isn't smoking going down the road. The mile per gallon problem isn't the engine.

 

What tires are you running on it?

I put a three inch exhaust, K&N air filter, and advanced the timing about 3 degrees and was averaging 12 for the year on mine. Where I am in WVa the longest stretch of flat road in the county is about 500 feet long, the rest is all hill either up or down.

I hauled lots of weight, towed lots of weight, plowed lots of snow, and the front hubs were locked in most all year.

Hauling 3 or 4 tons of stone, 9 MPG
Towing 5 or 6 tons, 6 to 8 MPG
Plowing snow, 4 MPG

Mine was 6.9, 4x4, 4spd, 3.55 LS, 9 foot dump, tool boxes, hitch reciever, snow plow sub-frame that weighs 8060 empty with me in it.
Speedometer was always wrong till I put 285/75R16 tires on it.