Hi All
First post after new (to me) first diesel. Ran a tank empty (by accident - "you have dual 37 gallon tanks"), on way home so put exactly 2 gallons in, bled air from filter with hand pump, took to highway at 55 on cruise and switched tanks. Drove until it burped again, switched tanks, and noted mileage. Comes out to 23.2 mpg. This is on a '93 F350 crew cab, long bed, E40D, with Banks Sidewinder, 4.10 rear, SRW, and barely legal 235/85r16's @ 85psi cold. I thought this was terrific but from reading forums is suspect. Other than possibly having broken pickup tubes and sloshing fuel masking real empty point do any other errors jump out? Foaming during fill obscures "full" so not repeatable. Oh, the "empty" tank only took 13+ gallons to fill so probably still had 5+ gallons in it. Thanks in advance for bursting my bubble ! GO 7.3. Does everyone just note gallons to top off and mileage and then correct odo like we did when you could see fuel in filler neck? Thanks for any response and sorry for length but I was elated for awhile.

Dick

 

your calculating incorrectly for accurate mileage.
here is the proper way;
before you start,verify your speedo is accurate.if its not,forget it.right down every single start/stop and use an online map to calculate your distance.

1.fill the tank (forget how much it takes,it doesn't matter right now.) and reset the odo.
fill it good,but there's no need to make a mess.

2.drive until your low.right around a 1/8th of a tank is fine.don't run out of fuel,it's totally pointless using this method.

3.fill up again.take note of your odo(or use online maps,and fill in every start/stop location you did,from the point of fill up,to the point of fill up),and how many gallons it just took to fill that tank.

if you repeat this method with consecutive fill up's,your only slight deviation between fillups will be your first and your last fill ups,with every fill up in between getting corrected with each consecutive fill ups,thus a very accurate average mpg reading.

the more fill ups,and more consecutive fill ups,the more accurate the mileage becomes.
10 consecutive fillups using this method,and you'll know exactly what your real world average mile per gallon is.with slight deviations between fill ups,and mpg peaks/lows becoming null factors.

i know for a fact,as of right now,my truck gets " 15.87 " MPG (13 tanks) w/approx 90% rural driving and loaded very often.w/speeds averaging about 45-50 mph (before the DRW conversion.)
quite impressive average with my loads,and such a large wind catching bed,as N/A to boot.
im now fixing a couple fuel leaks (that were present in my last two fill ups,slightly bringing my average down a little.i lost a couple gallons over the last two fill ups,so i think im slightly closer to 16 mpg average than it appears.) so i can properly figure my new avg as DRW.
so im stuck putting off my cowl induction mod,or any other mods(that would alter fuel economy) for 10 fill ups dangit lol.

 

if you are only able to fill 13 gallons, then yes your pickup tube filter is broken off. and i have really bad foaming issues as well. takes an hour just to fill my tanks. thats why i just put an in bed tank. fill that and let it gravity feed my main tanks.

 

Thanks but I did correct odo before switching to "2 gal" tank and was looking for a best at cruise number. Only reason I drove till it burped was that was the level when I added the 2 gallons. Now I know burp was at something like 5 gallons in tank which is why changeover and hand venting was so easy. Level in tank should still have been repeatable, no? I am keeping track of average also. Thanks again.

 

Your method is scientific at a glance but you are over looking the possibility of fuel sloshing in the tank. This means that while the fuel amount in the tank is consistent, the level will not be. This type of method would only be accurate if you were on a chassis dyno where you can be sure the truck will not move around. It really doesn't take much to throw things off when you are measuring a mere 2 gallons.

Averaging tanks is much more accurate, and the larger the fuel volume, the smaller the measuring error will be for each test.

I hear a lot about foaming issues when it comes to refueling but to date I haven't experienced it with my truck. I have the original vent tubes installed and working properly and the filler nozzle seems to be very consistent when it shuts off. Recently I got 2 consecutive fillups averaging between 24 and 25 MPG. Driving conditions were identical in both cases. Fuel amounts were aproximately 30L, and the distance a little over miles. I'm running by my odometer which I compared to road markers for accuracy.

 

Thanks for help. Will try filling other tank as ***-umed both would foam. Saw something about connecting vents but don't remember whether it actually improved filling. And yes, ODO was corrected with mile markers before I started. I just wanted a BEST highway number for friends criticizing such a BIG TRUCK during such energy poor times, etc, etc.

 

Tell your friends to hug a tree before your big truck runs over them......wacko's

 

If any tree hugger tries to give me a hard time, I am fully within my rights to read them the riot act.

I built, and road tested a highway capable electric car over the last couple years. Before that, I effectively doubled the MPGs of my truck to where its easily a match for the latest technology out there. I also work from home, so I have no daily commute, and our shop recycles all of our metal. I also drive used vehicles so I never contributed to energy consumption to build new vehicles.

In reality most activists are only good at screaming "we need to take action NOW!!!!". They are not smart enough to do it themselves or know what action to take, however. Often they are nearly broke anyway so they have a hatred for anyone that is able to earn an honest living and that ties into their hard wired suspicion of private enterprise.

Not saying all of them are like that but the noisier ones usually are. Next time you see a tree hugger telling you we need to make changes, do the world a favor and do them a favor; Tell them to lead by example and prove their ideas in the real world with their own money. If its so easy to "take action" then prove it.

I hope I didn't offend too many here, but thats how I feel after over 10 years following these issues.

 

David,
your totally blowing the 6.4l rigs out of the water!
i averaged around 10-12 with pops rig last summer.most claim about the same,with some people claiming to sneak into the mid teens with all highway driving.
the 6.7l scorpion is looking much promising with some upper teen reports now (though,these are not really "run in" engines yet.)
but still,they're not knocking on mid 20's!

your not matching latest technology.your mopping the floor with 'em old school style!

oh heres a cool thread (very new/fresh/active at time of this post) to share.you'll like this one.it's an IDI owner (likely reading this now lol) looking at a 6.4l rig:
https://www.ford-trucks.com/forums/9...-question.html

man is he in for a change when it comes time to buy fuel.let me tell ya.its not fun filling a 6.4l rig up as often as you need to.
sad part is,the IDI owner there,sports either a 4 speed or the 3 speed c6,neither with OD,and he's smoking a 6.4l in fuel economy.
hypothetically,set the 6.4 in place of his 6.9,and he'd probably see 6-8 mpg.

this just in from the 6.7l section:
i tell ya what.im glad im not caught up in the hp diesel battle wars.
the idi treats me just fine going the speed limit,even when loaded 90% of the time (and its not like i couldn't break the speed limit if wanted) ,with exception of big hills being the 10% i cant maintain the speed limit when loaded.i can live with it for the price difference.and shoot a turbo,would put me up to near,if not 100% full time speed limit for my uses should i ever(most likely next year,just for the fuel economy increase wile loaded) decide to add one.

the 7.3l PSD (at least first gens,i haven't looked into the '99's up at all.honestly i dont even know if those are the same engines or not as the first gen 7.3l's yet.my last psd to research a little) claim to be right neck and neck with our fuel economy on average.
however,i think that's from guys with the cats gutted and other emissions mods/deletes most likely.

 

Well compared to the 6.4, there isn't much to compare lol. I was thinking more along the lines of the scorpion since I hear they can reach the low 20s right out of the box. Although its not a fair comparison because that engine has an extra "fuel" you have to buy to run the emission system. Net operating cost is not really that of a true 20+ MPG rating.

But anyway I agree the 6.9 is a loyal engine and I will try to........HOLY CRAP!!!!

9 MPG from a towing 6.7? 16 MPG empty? I stand corrected! Never mind..... LOL

 

I have not read of anyone in the 2011 forum that even has the engine broken in yet. There are several mentions around of the pre production trucks out in the wild that consistently got in the mid 20's.

From what I've read and what I've seen of the 6.7 it looks to me like it's going to be a winner. I would love to have a 2011, beautiful truck inside and out. Too bad there's no manual transmission anymore, however reports are the new 6 speed auto is outstanding.

There's no way I can justify or even afford a $60,000 truck. Pay that much for a truck and it better be making me a whole lot of money every month. Heck I payed $38,000 for a 1 year old semi back in late 70's. Scared the heck out of me and the wife.

 

Pre production? What was the source for the info? Pre production could mean anything and they might not have been setup in a manner that could be produced on a full scale.

If it came from a ford press release, I am sceptical. I still remember their claims about the F150 hydraulic hybrid getting 60 MPG. In reality the truck was never even built yet they were happy to leak fuel efficiency claims and blogs like "tree hugger" where even happier to publish the claims without any verification. I agree that after break in things will get better but going from the example of the 6.4L, its not a very big difference. Even my truck was getting the high teens inside of the initial break in period.

 

Pre-production meaning the trucks that Ford had out in the field to companies like Halliburton, power companies ect around the country. I read so many articles over the last year, don't remember what magazines or websites they were on.

Some of the trucks had over 250,000 miles. I remember 1 in particular, seems like from Nevada or Arizona the guy reported almost 27 mpg. Hand calculated, lie-0-meter, I don't remember that part.

Anytime you start dragging a 5th wheel the size that people are pulling now and mileage on ANY vehicle is going to take a hit. Wind drag alone will be the biggest factor in mileage, let alone if you get into a headwind. I've had headwinds drop my truck down to 56 mph with foot flat on the floor so hard my toenails got clipped in the fan blades. Dropped mileage down to 9.5 from a 13 mpg average pulling my 5th wheel.

 

The mileage should come up with the urea systems, as they no longer need to run as much EGR as the older setups, but, still, another "fuel" on top of diesel still isn't as good as actually getting the mileage unassisted.
My work truck(08 D-Max ex cab shorty) seems to be a fuel mileage anomaly, pretty much everyone else I've talked to runs around the 15-16 us unladen mark, where the last 4 tanks together averaged 19(pretty much straight highway) which just happens to be about .5mpg less than my IDI was getting last I drove it, and that was with the T19 and running 70mph with 3.55 gears and stock tires spinning nearly 2700....

I hauled a 76 F250 on the trailer I always use (bumper pull equipment hauler) for a buddy of mine with the D-max, probably about 10K total towed load, and it dropped to 14.5, and that was taking it pretty easy and driving 55.
My IDI, PSD and Cummins would all hand that thing it's behind on a platter when it comes to mileage. Power, not quite, but, there's no reason a truck as laden with technology shouldn't at least match the mileage of a truck built 20+ years ago.

When it comes to calculating fuel mileage, the more fuel and miles you use to calculate, the more accurate the average will be. That 19 figure I came up with for the D-max is 4 tanks combined, not 4 individual ones, easy for me to do though, as I am currently running in the 4200+ mile a month range with it.