I am getting really bad gas milage out of my truck. I don't have a clue on what to check next. If I am just expecting to much out of my truck let me know, But I see people posting saying they are getting anywhere from 15-25mpg.

I am only getting 11mpg.
The worthless consoel says I'm getting 17mpg
01' F-350 4X4
Crew Cab, shortbed, SRW
7.3psd, Auto

4" exhaust
K&N Filter
I even have driven a couple of tanks with the Diablo Sport chip in the truck and it did'nt change.

What else can I try to increase this?

 

Just make sure you have a good clean fuel filter and more importantly than that, you have the screen behind the FPR is clean and not clogged off. Might even shim up the FPR while your in there too. If you have not... Then I guess the next thing I would want to know is what size of tires you have on her? Figure you have the 3.73 gears, so if you have much over 32" tires on her I see those trucks get worse fuel mileage than those with smaller tires or the 4.10's gears and bigger tires.

Then you might let us know if you have ran a tank or two of fuel system cleaner through the PSD also. I like to run some on mine about every 4-5 time I fill her up, I run the fuel conditioner all the time, just not the cleaner. Run the cleaner through with the chip on the hot setting too, this and go run the hound out of the PSD, will shot lots of fuel through her and help clean things out. Works good for me anyway. Keep the motor oil changed when you should also. I swear mine doesn't start as good once the oil is ready for a change. I can tell by the way she starts when its time for an oil change LOL. I dump my oil more often then not around here. 3000 miles and I am looking for a place to stop and dump and start over with new.

 

Rowdyone-
His truck is a Superduty, so his fuel system is different than ours. Most people say you can't shim the fpr on a Superduty, though some say you can.
My advice would be to get the truck scanned for codes, to see if something has happened to make the truck run in a default mode. If you don't care to do that, at least disconnect both batteries for a few minutes, and while they're disconnected, turn on your headlights to drain any residual power out of the system. Once you reconnect the batteries, you'll need to reset your radio and clock, but the pcm will have had any/all trouble codes cleared, and the truck just might run better and give better mpg.
Good luck.

 

Keeping your overdrive on all the time will help. Also launching it a little slower from a dead stop. If your driving is primairly stop and go on city street, then it will be low until you can get some freeway miles.
Also keep your aircleaner clean. I just tapped out my K&N filter, and now get much better throttle response.

Leo

 

Yeah, I thought the SD's could not have the FPR shimmed, but seen some PIC's of this very thing on here a week or so ago. Then went out to a friends house with my fuel pressure guage and asked him if he was game to try his. Well long story short, a stainless allen head machine bolt with a little sanding and trimming and it shimmed right up.

I had been told for ever that you couldn't do those, but seen the process here in someones PIC's and you can. Not really any worse than our OBS trucks either. A rag under the FPR is a good thing to do though. I don't do that on mine, but someone elses truck and I get way more careful LOL... Besides everyone elses trucks are way nicer than my old GWE...

 

steve95gt,
I hope I don't ruffle too many feathers, but I wouldn't believe everyone's claims of great fuel mileage either. I am on my third Powerstroke. First one was a 1999 4X4 4 door dually, then a 2001 Excursion, and now a 2003 F250 4X4 4 door. All have been automatics, all have been 7.3 PSD, all have been 4X4. I drive at least 60,000 miles a year, towing a trailer about half the time. The only non-stock item has been BFG Radial T/A's on the F250 and Excursion, one size larger than stock. I get about 13 mpg doing 75-80 expressway driving no trailer and 9-10 mpg with light load trailer. Sure, I get 17-18 mpg at times, usually at night with no traffic and doing 60 or less. This has been for ALL 3 VEHICLES, so I think it is a good comparison. The guy that tells you he's getting 21 mpg pulling his 32' 5th wheel? Well, I would guess (only my opinion) it's @ 40 miles per hour with a tail wind and down hill both ways.
If fuel mileage is a concern, sell the PSD and get an F150. Superduty's and Powerstrokes are meant for work and hauling, not fuel mileage. If you want the big truck, get a big wallet. Good luck!!

 

Sorry, but an F150 isn't the answer for fuel mileage, either. I know a few people who own them. With the 5.4 V8, they seem to average about what my PSD does. But, put any trailer behind them, and the mileage plummets.

A friend has a company that uses F150 4x4s. His fleet average is less than 12mpg. When one of his guys pulls an empty water trailer (500 gallon trailer, but empty), the truck gets about 10 mpg.

My 4x4 F250 PSD automatic averages about 15 - up to 17 on the highway. I loaded it down with a bunch of junk, pulled a 3k pound trailer on the freeway (55 to 60) for about 200 miles. Got 14.4 mpg. Not bad.

But, if you really want to get GOOD mileage with a PSD, it seems that you need to have a truck with 1) standard cab, 2) XL trim (XLT and Lariet add a lot of weight), 3) 4x2, and, most important, the 6-speed manual. The autos help it to suck fuel.

 

I agree! I was thinking some people are full of it, but a thread I saw made me realize that some people post MPG numbers based on the overhead console readout. That is the only explaination that makes any sense for some of these outrageous numbers people claim. I mean nobody is just BSing right? They are legitimately mistaken.

I do the math on every tank and with winter diesel, in-town driving, and hubs locked during snow storms, I'm not getting better than 11mpg.

 

Not BS'ing anyone, I live 17 miles out on a 55mph highway, with the economy tune predator, 4-inch exhaust and stock tires at 55mph litefootin' it I got 21, but with my 305's on 16x10's it dropped to 18.5, if I run it harder (67-2k rpm-72-73mph) it will get down to 16.5-17. It seems to be fairly decent, and some people claim better, some worse. I have a 00 reg. cab, XLT 4x4-6-speed. If fuel keeps going higher I think I'm going to switch back to stock rubber.

 

I would sure figure that you guys that get less mileage than a F150 with the 5.4 really have the PSD mismatched with tires and/or gear ratio. That , or your driving well over the 70 MPH mark.

My wife has a new 5.4 and we are really sick of its fuel mileage, let alone my 10 year old PSD out fuel mileaging the 5.4 is way stronger also. I have not been impressed with the 5.4 at all.

I do think lots of guys have the tire size and gear ratio wrong for good fuel mileage though. I see that around this are and most of them with the 3.73's running tire sizes over 33" all have poor fuel mileage. Just what I see around here anyway. I have 33's on mine now with 4.10's and have been pondering trying 35" tires to see if I could bust 20 MPG. I am afraid right now it may get me over the threshold and get my fuel mileage going down though.

 

Rowdyone what is your MPG now?? I figured with the 4:11's and 33's you would be getting poorer mileage than us guys with 3:73's. I figured my main mileage drop was because of the added width of the tire. I was trying to run a slightly taller tire to drop RPM's,

 

I consistantly get 17.5-18.5 mpg. I have an 01 CC XLT auto, Stock tires. On interstate I keep at 70 mph and on the highway I run 65 mph. No fast starts from stoplights. You can get good milage, but you have to drive right.

 

Turbo6 - I wish I could get that kind of mpg! Just to clarify, you really derive those numbers by using yor trip odometer, reset on every fill-up, and divide the miles driven by the gallons pumped in, right?

I don't mean to sound silly nor am I accusing you of B.S.ing, but I really doubt most of the mpg numbers posted on FTE. Since you have the decimal place in your numbers I am betting you really do the math.

I do believe that PSDs get significantly better mpg on the highway. I had to travel on the highway a lot this past week and I noticed when the tank was 1/2 full, I was way past the usual number on the trip odometer.

When I bought the truck I drove it 600 miles to get home. I made 450 miles on one tank. As I found out later that was with a old air filter and under-inflated tires.

My daily driving is 50-100 miles a day, little of it highway, and usually with a load of tools in the back. 13 mpg is the best I seen before it got real cold last early December.

 

Guys with the 4.10's and with the OEM tires which were way smaller I was getting at best 12 didn't matter if I towed or not either. Went to the wider and taller 33's(305's) and gained 1-2 MPG and she was like that driving 70 MPH if I slowed down to say 60 she would get better as this truck was built when the speed limit was still the 55 MPH stuff that was some kind of a pain here in Texas LOL...

Since all that and now with the same style tires and size just several sets later, I have added a host of mods to the motor thanks to the reading here and helping others around here with their PSD's, I have her getting 16-19MPG on the highway which I feel is really good with the 4.10's.

Would love to try a set of the 315's to see if I could bust 20 MPG, but I fear that my tow would be wiped out for a good heavy long tow anyway. I have about talked myself out of the 315's over the last few days and may just stick with the 305's after I do the reverse shackle and level the front with the back.

I probably could just set the cruise at 60 and get the 20 MPG now if I didn't enjoy the driving at 70 or more LOL...I get the RPM over the 2300 mark and I see the MPG run right down to 15-17 range really quick. I already run the fuel conditioner all the time too. Still really can bitch much about the fuel mileage she gets now with how great this 10 year old PSD runs. She really runs good for a good ol'e big white tank that she is.

PS edit. I forgot to mention why I got the big spread of fuel mileage posted here too. Its an average with many tanks of fuel, as I have a log I keep with this truck since she was just a new kitten and ever gallon of fuel is in the log as well as the maintance.

What I have seen with this truck, is that it depends on the pump nozzle as well as the angle in which the truck leans when filling up to how much fuel you take on when you fill her. It can make a big difference trust me, even if you fill to the top of the filler neck, you need to do this at the same angle and the same pump if possible for a good set of numbers you can trust. Then figure this on your on as well too, not let the console do this for you.

I think a lot of the figures guys here have mentioned have been real numbers alright, just that they may have not taken on the same amount of fuel each time which can make a huge difference either way too. Just things to think on anyway...

 

I have a 99 F-250 7.3 PS and just recently completed a round trip from Ohio to the Daytona 500 and back; all interstate travel and I kept good records and calculated my down and back mileage. Down was 17.3 and back was 17.1. Drove about 70mph down and about 75mpg back.--Medic 66