can anyone tell me why my stock 5.4 04 supercrew only gets 380 miles per 30 gallon tank? i drive between 70-80mph and run the ac on level 2 and do not have any modifications nor is my check engine light on.....this really sucks

 

i have an 08 mods in my sig

i get the same on a 28 gallon tank

it sucks horribly

 

I have the same size tank but I get about 500 miles to a tank full which is about 16.5 mpg, I have 2wd w/22" rims, Edge on level 2, 87 octane w/ a/c most of the time.

 

I have the 35 gallon tank and usually fill up at around 400 miles(usually around 3 to 4 gallons left in the tank) if driving in town. About 500 miles if the tank is mostly highway miles.

I get anywhere between 12.4 to 14 mpg in town and anywhere from 14 to 17 highway. For some reason my highway milage is never consistant.

Edit: 4x4, 3:73 gears, 5.4 motor, and scab 6.5' bed.

 

My MPG is similar and exact truck configuration except the fuel tank size. Not to digress/hijack, but do you have pictures of your gas tank. I have the 26gal one and it just isn't enough, not sure where Ford is getting an additional 10gallons of space from... Thanks.

 

How many gallons are you putting in when you fill up? I doubt you're putting in exactly 30 gallons or you'd be empty.

380 div by 30 12.6
380 div by 27 14

Just 3 gallons raises it 1.5 mpg.

Plus anything over 65mph really starts sucking fuel. Really anything over 55 starts sucking fuel. FX4? 3.73 gears at 80mph your running around 2100rpm or so?

Use your cruise as much as possible and stay within the posted speed limit. Have you changed your fuel filter lately? Air filter? Check tire pressure on regular basis? Change oil and check oil level on regular basis? Any extra baggage in the truck that can be taken out?

 

yeah...its a fx4 with 22'' wheels...just changed air filter and oil...used to have the edge evolution and was only getting 393 miles to tank....i top it off every time i fill it up and i run it completely out and carry a gas can in the bed.......i have the original window sticker and it states a 30 gallon tank.it is a 2004 with 373 gears....something just dont seem right....i did manage 422 miles out of it when it had 50,000 miles on it...it now has 96,000 but i cant see why it would drop 40 miles per tank and my driving style hasnt changed if anything ive slowed down a bit

 

Is your speedo calculated to the 22" tire? I think the 04 FX4 came with 17" tires. Correct? The reason I ask is because if it's not calculated you're traveling further than what your trip thinks you are with the larger tires.

 

Just some thoughts. You really need to do the math. Keep a record of gallons used per each fill up and mileage driven, to get an accurate calculation. Also note where you drove or if it was different in any way. Weather, highway, etc. The 22s will cut about 1 1/2 mpg off of mileage, compared to stock. Also, if during that period, they started adding 10% ethanol, that will cost you a mpg or so. As was mentioned is it recalibrated for a taller tire or where they near the same.

 

they were the same heighth as my stock 18'' rims and the bf goodrich tires....about 31'' tall

 

yea everyones on track with the wheels and speed and ethonal blend fuel and what not. but running the tank out of gas is risking the fuel pump. the gas is what keeps it cool. and i'm sure new spark plugs will help if they've never been changed, and a bottle of techron fuel system cleaner should help a little bit. my little 5.0 gets me 23.5mpg when i do the speed limit and when i do anything over 70mph it goes down to almost 13mpg, sometimes worst if i go through the mountains.

 

Ok, so no recalibration necessary, but I bet they ar much heavier and the tire is much wider. The weight and the resistance are mileage killers.

 

Right on, I almost never go below 1/4 tank before filling up.

 

Question for the OP is why do you run your truck completely out before refilling? Just curious. You can still check mileage without using up every last drop.

 

i dont usually do that.......i did it too see on the last tank how many miles i would get.....i barly went over 75 on this whole tank of gas