I dont fall in that category as I have 75 total gallons capacity with the upper toolbox tank plumbed into my middle tank. I could probably go 1200 miles on one complete fill up, front and rear. Have I ever filled them BOTH up all the way, the answer is NO. It would cost me 300.00 in fuel.


I am figuring that at 16 mpg.

 

no if you do the math both tanks are about 19 depending on model year blah blah blah 17 mpg 646 until burn out, you leave 4 gallons per tank then you are in the 500 mile range, you are not far off. And I have driven 603 miles on a tank (sweating a little bit) all free way at 65 mph, I got 18.7 mpg. best MPG I've ever seen 21.3 through wyoming with a 40 mph tailwind (wish that was every day) I drove over 700 mile on a tank of gas (would have been further but the gatorade bottle was full??? )

 

Nothing new, it can only be done 1 way, correctly that is. I assumed you were doing it backwards from your post. I'm so confused

 

De-confuse us all please and tell me/us the one correct way.

 

i cant believe that. I really need to do the 10k mod and the fpr shim to see if that helps any with mine. I can get 420 to 440 miles on a tank and 90 percent of that is IN TOWN driving, but people say that they squeeze 550 to 600 miles before filling is giving me P ENVY......... thats POWERSTROKE envy for all you pervs that thought I was talking about something else. LOL

 

2 thoughts on this...
1. I believe this is Illegal to do.
2. I wanted to do this before I found out #1...

 

PSD ENVY? All my friends are going Cummins.

 

Thats news to me........of course out here they dont pull over diesels ever other than the over the road big rigs.

 

My '97 F350 SRW holds 18.2 gallons in the rear tank and 19.0 in the front tank. On separate occassions, I have run both tanks empty to see what they would hold.

The rear tank has taken up to 17.5 gallons to fill up and the front tank has taken up to 18.5 gallons to fill up. My driving is in-town and highway commuting. I normally switch to the front tank after the odo shows 280 - 285 miles. I'll go 10 miles farther on the front tank. That gives me a range 570 - 580 miles on both tanks before running out of fuel.

I shimmed the FPR and added Diesel Kleen this past weekend when I filled up. That was at 553 miles and about 33.5 gallons for an average of about 16.5 mpg. I'm generally in the 16.5 - 17.5 mpg range. I started towing a 24-foot travel trailer recently. On my trip from California to Idaho, I managed 12 - 13.5 mpg pulling through town and at highway speeds.

Math involved: ODOMETER reading divided by GALLONS at fill up equals MPG.

 

we need to keep one thing in mind.RPMs what gears,tire size are you running? The 3 .55s will definitly get better mpgs than 410s. Larger more aggressive tires will lose mileage and throw off odometer as much as10%.With all do respect mileage reports always taken w/a grain of salt..

 

That makes more sense to me, lots of variables.

 

I've been getting around 19.5 MPG pretty regular with my mods & Diesel Clean. I just recaculated the other day. That was with pretty much no loads & A/C on all the time.

 

I don't know where you're going with this but you already stated the one and only way MPG can be calculated. I'm not trying to be a smart azz but you stated 20 MPG and quickly restated 18.5 after you discover the size of your fuel tank. That's the only confusing part of this entire thread, which bkcowboss explained, it seemed like you were "eyeballing" it. There is no way I can know your expertise or knowlege so when I post answers in this forum so I assume you know nothing. You wouldn't belive the questions that are asked in these forums that make no sense at all.

 

Guys, there is not much to get 20 miles to the gallon with these trucks. Mine is 2wd,235/85/16E tires, and has 410 gears. Nail the speedometer down at 60mph and get 20-21 mph all day every day. Just keep the motor below 2000 RPM.

Personnal best was in 1997 went in andout of the north rim of the Grand Canyon and up to Lake Powell got 22.3 MPG. 55MPH road.

 

This is how I do it:
Start with a complete fill up and reset the tripp od to 0. Drive until normal fill time. Fill it back up. and divide miles in to gallons. EXAMPLE...... Lets say you filled it up and reset the OD and drove 240 miles. You then filled the tank back up and it took 16 gallons. You got 15 miles to the gallon.

Miles/Gallons=MPG
240/16=15
BTW, this is my normal milage, any thoughts? besides to slow down.