I bought a 1999 F350 PSD DRW a month ago. The previous owner reported getting 18mpg on the highway and 13mpg in town. I was ok with that, thinking I would get a little better. I was wrong. I struggle to get more than 12mpg. Ran 320 miles yesterday non stop and got 13.462. The truck was empty and the cruise control set at 75mph. It does have 410 gears and the tach sets at 2250 rpm at that speed. Do I need to slow back to 65 and 2000 RPM to start getting better milage or is there something else I am missing. The truck seems to run fine and never hesitates or has trouble maintaining its speed.

Thanks in advance

Rod

 

I've been told once you exceed the 2000 rpm the 7.3's start to drink the diesel. I usually keep it at or just under 2000 (around 65-68) and get 20 to 22 mpg on the highway.

 

you might want to check and clean the ebps and tube ...they can become very cloged up ... mine was clogged and had a hole in the line cleaned and replaced it and i got a lil better mileage

 

Could be a case of exaggeration. Like when a honda driver tells you his ET, you've gotta add five seconds for the real number.

 

slowing down will help for sure - think about it this way - you're in a nearly 4 TON truck that has the aerodynamics of a large brick - add in the 4.10 gears you've got, and i'd suspect that the PO drove around 60MPH or so

 

My Honda will do 12's in the quarter, even with me on board - MOST Civics are posers, but there are those that will stomp a mudhole in ya

 

Your mpg is about where mine was two years ago - before I discovered this user group . Now my mileage is consistently above 16 mpg with an occasional 18-20 mpg tank (though rare). A rule of thumb is that for every mph above 55 costs you a 0.1 mpg...so if we applied that to your truck (going from 75 mph to 55 mph) that would add 2 mpg to your mileage - bringing you to approximately 15.5 mpg. So it looks like you get your mpg up by about fifteen percent by just slowing down. At 65 mph you should be seeing roughly 14.5 mpg, all other things being equal, based on the rule-of-thumb. My sweet spot for mpg is at 2000 rpm, 62 mph.

You might want to check a few things that I found helped me...change oil to 5-40 syn (Rotella T), change gear oil, change intake filtration (99's had an awful airbox - search for AIS OR 6637 mod) and do the zoodad mod. You might want to consider a tune from dp-tuner (an economy tune or a light tow tune might help a little - but it will definitely make your truck run better). Finally, I would read this paper for some hints:

http://h1.ripway.com/nlemerise/Ford/MPG_Secrets_Whitepaper.pdf

Good luck and let us know how things work out for you...ask lots of questions, there is some serious knowledge here on FTE!

 

I wouldn't want to go heads up with you in the 1/4 mile with my Nova!

 

Ain't that the truth! And Neal is one of the sources! Big kudos to you & the other gurus that help us all out.

 

No, because my technique SUCKS - and for the record, my Honda is a 1000cc sportbike - the right tool for the right job!

 

Guess my mileage isn't that great either. I just finished a 1100 mile trip with the cruise set at 70, and the chip set at 80 econo, and the AC on because it was over a 100*
Empty on the way over and a 500# motorcycle in the back coming home.
Averaged 17.25
RPM was right at 2,000
Last year in cooler weather we took a ride and averaged over 18.

 

Well thats no fair...

 

There is nothing wrong with that mileage (17.25 mpg at 70 mph)...nothing at all! Above 40 mph or so, I see no difference in fuel mileage with the AC on or off...aerodynamic drag due to open windows offsets compressor cycling of air conditoner. I have had trips where I averaged for the trip 20 mpg (this summer from Reno to Kingman, AZ, as an example), but it is a slight downgrade. So I don't say that my mpg is down because I get 16 or 17 mpg at times...different grades, different winds (love a tail wind from here to Kingman, but we usually get south winds), different tires, different loads, different barometric pressure, different temperature...the point, your trip last year cannot be the same trip as this year - even if it goes to and from the same place.

 

Racing is about winning! I'd love to have a 12second PSD, but it's an 8000lb truck!! let's put the same power in, say, a 4000lb vehicle... Carroll Shelby put that thought to very good use!

 

17.25 sounds pretty good to me. That's about what I get at 70-75 on the highway. I just got over 18 for the first time driving back from FL. That's with all the mods listed below, in the 80 econo tune, with an occasion forray into the 120 Race so soot the occasional numbnut. Best I got before the DP was just over 17.

Joe