if this is true, you are the exception, not the rule.
I've not had good experience using seafoam as an injector cleaner. I did pick up about 1-2 mpg using 3 cans of injector cleaner (1 can was good for "an average sized" gas tank of 14 gallons) when I first started driving mine.

You should also pay attention to your oil level. My 5.4 is extremely sensitive to being low on oil, and we went from 12mpg to about 6 in just 300 miles. Yay slow leaks.

You're not towing a trailer with a mesh ramp, are you?

As for the hose, I got nothing.

 

I believe the hose is the temp pickup for the automatic temp control. It goes to a small grille on the dash, just to the right of the steering wheel.

Last month, I unwittingly left the hubs locked when the ESOF failed to disengage them. The transfer case was in 2wd, but the hubs remained locked in. Economy over a 180 mile trip was down to a frighteningly dismal 9.5 from the usual mildly terrifying15+ I get on that run. Not saying that's your issue, but it could be a contributing factor.

 

4 mpg wold be enough fuel to wash down cylinders.

I suspect you have a leak in tank or a pin hole in fuel lines.

this could be dangerous, get this worked out.

 

Latest: I'm just above 1/4 tank. Done 180 miles.

Should get around another 50 miles I guess?

Where best to start if there is a fuel leak? Stupid question: I should see it/smell it in the snow on the driveway, right?

 

Holy smokes that's bad mileage!
I would think a fuel leak of that size would be obvious, especially if you have the EX sitting still idling for a short while, should build a puddle/wet spot or at least produce a strong gas vapor smell. ANY FUEL LEAK needs to addressed ASAP.
What size tires are on it and what pressures do they have in them?
Those front hubs may not be unlocking when you turn them off the locked position, you can reach behind the tire and try to spin the U joint inside the steering knuckle, an unlocked hub will allow the joint to spin, a locked hub will not allow any spin. (everyone except 00t444e sees a drop in MPG from a locked front axle ).
Exactly how "urban" is your usage?
"My idle time is minimal, normal at best." I don't know what "normal" idle time is in frozen MN, do you let it sit idling at all other than stopping at traffic signals?
Any check engine light? Does the Check engine light light with the engine "off" and key "on" (function check)?
Something is very far from "normal" to have MPGs that low.

 

 

1st make sure your mileage calculations are correct. Floats can go bad and make guage read low but you still have lots of fuel left.

2nd make sure locals haven't devised a clever way to siphon from your tank.

3rd crawl under vehicle and look for wet spots. Mainly around connections and filter for gas pressure line. Then inspect return line to make sure it's not leaking.

4 mpg at 60 mph is .25 gallons of fuel/ min. Or if my math is right 90 pounds of fuel/ hr.

our injectors are 19 lb/hr units so 10 = 190 lb/hr.

Basically your going thru 50% of the motors ability to use fuel. That's like running at 0 vacuum at 3000 rpm all the time.....no idle no stop lights etc.

your not using that much fuel, your losing it or your mileage calculations are wrong.

1 of my excursions show about 200 miles on odometer and 1/4 tank of fuel left. Typically I put 18 to 22 gallons of fuel in before the nozzle clicks full and guage reads full. My float must be bad as I know my tank holds more than 30 gallons.

 

I usually only USE just over a quarter tank in 180... granted that's of purely highway.

A fuel leak this bad should be visible on the driveway. go to an appliance store and see if they have an old refrigerator box that you can place under there.

Pull your engine oil dipstick and smell it for a strong fuel odor. rock2610d is right that it's enough to be washing down a cylinder. a failed injector could be just dumping fuel in, which would leak down around the rings.

 

That's an interesting experiment. I'll run this tank as low as possible first and then fill up from 1/4 tank next time.

Idle time: just traffic lights. My urban driving is all town driving (around 20 miles a day) with a little highway thrown in sometimes (5 miles)

Engine check light functions as it should. No warnings - would that mean O2 sensor is functioning okay?

Got underneath it this morning to quickly swap out my reverse sensors and my cursory look didn't reveal anything obvious... the snow doesn't reveal anything either.

Got the stock size tires on it. No lift. Front have 47PSI and rear have 52 PSI - so a slight imbalance from the 45/55 it should have.

I checked the oil dipstick. Can't say it screamed of smelling of gas... nothing outside of what I'd refer to as abnormal?

I'm as empty as my fuel tank often is.

 

 

Everything is stock.
MAF is cleaned. Throttle body too. Haven't replaced the plugs yet.

 

Please post up EXACTLY how many gallons (from the gas station pump display) this next fill takes and the trip Odometer reading at that time, it might help to sort some of this out. As you can see, you do have several folks looking to help improve your mileage.
It doesn't really matter how low you run the tank before a refill to full, as long as the last refill was also to full.

 

Got it, will do. Last refill was to full, the receipt says it was a 35 gallon fill up. At every refill, I reset the trip odometer - a habit I've been doing for years.



Y'all are great. Really appreciate this community

 

to go 200 miles on 35 gal is 5.7 mpg, which short of towing massive loads uphill, should never be seen.

And you're certain that nobody is resetting the trip odometer on you as a mean joke? or does the mileage add up to what you've driven?

 

Haha, yes I'm certain. Only I have the one set of keys.

To confirm, my last fill up was 35 gallons. I'm just a hair above 1/4 tank left at 185 miles on the trip odometer.