Sudden 3mpg drop

BgBlDodge

BgBlDodge

Hates hippies
Joined
May 7, 2007
Messages
16,647
What would cause this? My last six tanks or so have been 3mpg lower than normal. I went from getting 16-17 to 13-14 and I haven't changed anything. I fill up at the same station, same pump, drive the same route, drive the same way. I've run fuel cleaner through it, I've run the truck hard to try and clean it out, I've cleaned the MAP and IAT sensor. I don't know what would suddenly cause this. Tire pressures are good, air filter was cleaned a couple of months ago.
 
Might be time for a filter change but my pressures haven't dropped any. Worth a shot though. I don't think southeast texas gets winter blend diesel. Heck, it's 81* right now. LOL
 
Mine seems to have done this too lately. Wierd. A plugged fuel filter would rob horsepower and make it actually get more miles to the gallon wouldn't it? I have been runnin' a little red contraband lately due to this bull sh*t $3.39 a gallon. Freakin' off-road is $2.98!!!! Maybe they winterize the off-road due to the equipment sittin' all winter but I have no idea what would cause yours to do it.
 
Me either. I could see one bad tank but 6 in a row? I'm struggling to get 330 miles to a tank now where before I was knocking down 350-400 on 3/4 of a tank.
 
A clogged filter can lower your fuel milliage by a couple miles per gallon. We have customers come in all the time who complain there milliage dropped. We suggest they replace the filter and it most always fixes their problem. Running fuel cleanner in the system can also cause the filter to collect more dirt. The cleaner helps clean the tank, and lines and it ends up in the filter. It is usually a good idea to run the cleaner a tank of two before you are going to replace a filter to keep the system as clean as you can.
 
I'm gonna try changing it. My fuel pressure though hasn't budged though. Still holding the same.
 
Mine dropped one time and the culprit was the drum brakes in the rear .
One side or both ( I don't remember ) but under the 5.9 power it wasnt noticable. Anyway one wheel or both were unusually hot. Well the slack adjuster deal is supposed to automatically tighten up and it did, like to much.
I don't know what caused it other than it could of been that the pads were so far gone that the rivets or whatever holds the pad on dug grooves into the drums (pads was completly gone ). Just a thought.

Also I know it isn't winter blend but like three times now in the last couple months the fuel has been clear as can be vs the usual super green. The old man says it smells like a Varosol mixture ( which has less lubricity and BTUs )and he thinks that is what their dumping.
Do you look at the fuel when filling?
All fluids levels in check?

Just a couple thoughts seeing that you have covered the most likely already.
 
I've got disks in the rear so no worrying bout drums. I'm wondering if they aren't cutting the fuel with something. I'll check next time I fill up.
 
My truck just did the same.The only thing I did was a Edge Comp which I thought the extra timing would have helped it,bigger turbo,fuel pump,4" exhaust & I adjusted the front band which was way loose.I set it at 2 rounds out book said 1 7/8 out & I know people that run 2 1/2 out???:redx: :poke:
 
I dropped 4 mpg, 6 months after my new VP, preassure never dropped, never had any dead peddle, changing all fluids and filters didn't help. Sent the pump in to be tested, said it was good. Crapped out a week later. Almost turned me common-rail.
Hope it's not the same for you.
 
I would still lean towards winter fuel...I really doubt they ship unblended fuel to Texas and the SW. What happens when a truck fuels up there and heads for colder weather?

Chris
 
Chris as far as I know we never get winter fuel down here cause it just doesn't get cold enough. I dunno. I'm gonna swap the fuel filter out here today and see how that works.
 
Ive heard that the apps being maladjusted can cause mpg drop ,but it usually has a stiff pedal first right?
 
BgBlDodge said:
What would the trans/converter have to do with mileage?
Click to expand...
A loose converter is less efficient that a tighter one, it allows more for RPM’s, which is wasted energy. I’m not saying that’s what caused your drop but that’s what a bad convert/ trans would do. I think how to get better MPG’s is a mystery because I’m getting 17-18 mpg in Oregon and in California I only get 13-15. It’s not the fuel’s either, because I’ve been running fuel from an Aug. tank in the bed and it was full of California fuel. It might have something to do with the amount of smog that’s in the air. Who knows?...


-Rob
 
4x4dually said:
Mine seems to have done this too lately. Wierd. A plugged fuel filter would rob horsepower and make it actually get more miles to the gallon wouldn't it? I have been runnin' a little red contraband lately due to this bull sh*t $3.39 a gallon. Freakin' off-road is $2.98!!!! Maybe they winterize the off-road due to the equipment sittin' all winter but I have no idea what would cause yours to do it.
Click to expand...
If a guy wants to run “Red” fuel, that’s his business but I wouldn’t advertise it… It’s a rather expensive ticket if one were to get caught. Chances are, you’d never get caught and you can save all sorts of money but if the wrong person hears about it, from your area, who knows the out come, ya know.

-Rob
 
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