recentely i noticed a decrease in gas mileage on my truck and i was wondering what i should be getting. i have a 125,000 mile 1991 f250 diesel 4x4 with std cab and manual transmissision. when i first got the truck i got 19 miles to the gallon on the highway then the truck started to run rough so i replaced all the injectors with new ones. since then i now have alot more power but i am getting only 15 miles to the gallon. what do you guys get for gas mileage? any ideas? Thanks mike

 

I have a crewcab 4x4 with 4.10 gears and manual. I consistently get about 14 mpg.

Jason

 

Have it retimed. If the timing was set properly for the opening pressures of the old injectors (which were lower compared to your new ones) then the timing would be off. Timing has a lot more to do with fuel mileage than a lot of people think.

 

On the re-timing, I have a 1993 ATS which I changed out the gears from 4.10 to 3.54. After the gear switch, have noticed significant loss of power and fuel economy. From 18 to 14 mpg and lot more black smoke. What should the timing be set at for an elevation of 4500 - 5000 feet? Is this something a shadetree gas engine mechanic can do or should I face the music and take it to a diesel shop?
Thanks

 

Well to set the timing you need a Diesel Pulse Adapter, these are hard to come by used, I looked for over 2 years until I stumbled upon one, they will allow you to use a timing light. New ones run over $300, and the only used one I found went for $125, which I promptly jump upon.

Now for the settings.

5 deg BTDC @ 1400 rpm for the 6.9 and 8 @ 2000rpm for the 7.3

If you don't have one of these pulse adapters, then yes you will need to take it to a shop to be set. Just remember that the engine needs to be warm, and to unhook the Tiiming advance solenoid on top of the injection pump so that you get good readings.

 

I have a Y2002 F350 7.3 PS Turbo with 48K miles. My gas mileage is 12 miles per gallon no matter what I do. I need some serious help/direction. I pull a 5th wheel and get 12 mpg. Around town I get 12 miles per gallon so I need advice. When I hear all miles per gallon it is hard to believe. I know this is an old subject to many of you. Is there a new computer chip available or is there some type of upgrade that I can get to improve my mileage. Nothing has been done to the diesel since I purchased it new in Y2002. Open to suggestions.

PistolPete

 

PistolPete,

Welcome to the forum.
I'm not sure what could be done to mod the fuel economy of a powerstroke. I am loyal to mechanical diesels. You might get better help on the powerstroke forum.


mledwards_1,

I think having it timed will be a good idea. Through careful tuning (trial and error) I was able to bump up my mileage and cut back on exhaust smoke as well. I don'r recommend trying to dynamic time it yourself unless you know what you are doing. The catch is that not many diesel shops still know how to time these older diesels since there is no scan port on them. What sort of smoke are you seeing when driving? and change from when the old injectors were still working properly?

For the record, I can get slightly over 20 MPG @ 70 MPH on a good day, so it is possible to get good economy out of these trucks but it takes some patience.

 

just calculated my mpg, last tank whick was mostly city i got 16-17 mpg.
on longer trips over highways i can get about 21-23. and thats going through mountain passes.
i just turned my fuel up one flat last oil change, with noticable power increase and very noticable black smoke increase. so im gonna turn the fuel down half a flat next oil change as i dont tow very often, and i drive like an old man (im 19).

im happy with the fuel mileage i get.

 

Not much flat ground here on the island either, This is BC after all.......the windy weather hasn't helped much either.

Driving gently will make a big difference, but even with the ocasional lead foot start off and holding with the flow of traffic, its doing pretty good lately.

I'm trying to get an average of 20 MPG over several fillups to confirm my results. So far, so good.