MPG loss no reason in sight help!

[dixiedevil]

i have a 2000 model 7.3 4x4 since i have owned it i have used mobil 1 full syn oil diesel kleen max hp with every tank change fuel filter and air filter at least every 8k to 10k i was getting 21 mpg for at least 5 yrs now all of a sudden i'm getting maybe 10 to 13 mpg i have cleaned back pressure sensor tube and installed new sensor also put a new injector pressure sensor still no change i have a new sending unit to put in tank since fuel gauge at 1/4 tank is dead empty dont know if sending unit would cause mpg drop or not i'm outta ideas truck is not throwing any codes it runs great no power loss so really none of this makes sense to me for such a mpg loss all of a sudden

any suggestions woul be great also i have installed a dyna track freespin kit as well.

[hucorey]

Talk to your local oil/fuel delivery guy and ask him if they are using B20 for winter blend. If so, try and find some straight diesel and run a tank full. Lots of people on here from all over have said the same thing as you including myself about our mileage drops for no sensible reason.

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[TSbeanspowerstroke]

check for boost leaks as well as exhaust leaks, i would also check the fuel bowl drain valve for leaks as the seals go bad on there all those are are 2 o-rings.

[shmuckaluck]

Hey guys,
Not to ignore your real problem but, there is no way you are getting 20 mpg with a 2000 7.3 4x4, I just don't believe it, so maybe thats half the problem. I really not trying to be a smart ***, just if you are getting that whats your secret.

[TD444EVER]

maybe your front bearing are bad? extra drag?

[hucorey]

Its not uncommon to get 20mpg. I got that when I first got my truck. It was all stock with only a super chips programmer and straight piped. I don't get that anymore though after all the mods I have done so far. Summertime I get 18-19, winter is 15.5-16.5.

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[grhath]

I'm having same problem with my stock 6.0. About 4 weeks ago I changed my fuel filters. I was getting "water in fuel" warning and after draining the module 3 times I still got the warning. So, I change my filters (wix brand). No more warning. I noticed that same week that my economy dropped from averaging 15-16 mpg down to 12-13 mpg. Truck runs fine (the same). I cleaned EGR (not too coked) but hasn't made a difference. I noticed the drop in economy on the computer and confirmed it with manual calculations. I've got my diesel from 3 different locations all with the same results. I've had my truck for 5 years and never noticed a swing this much before. I used Ford's diesel fuel treatment on last 2 tanks...no difference. Don't know what else it could be?

I haven't towed with yet, but I'm dreading it. I usually tow my 7k lb boat/trailer and average what I'm getting without towing.

Any help?

[grhath]

My last post....I should clarify that I normally get 12-13 mpg while towing that trailer, which is what I'm experiencing right now without towing. I re-read my post and saw it may be a bit confusing.

[grhath]

One more note....I also could get about 21-22 mpg on the highway at 55 mph, at least before this problem. Now best I see is 17-18 respectively.

[blderman]

Originally Posted by shmuckaluck

Hey guys,
Not to ignore your real problem but, there is no way you are getting 20 mpg with a 2000 7.3 4x4, I just don't believe it, so maybe thats half the problem. I really not trying to be a smart ***, just if you are getting that whats your secret.

I can pull down 20mpg on the highway very consistently(65mph or less). My mods are in my signature. Biggest change occurred after up-pipes and new injector o-rings. My truck weighs in at just under 9,000lbs with my daily load of tools. If I exceed 65mph or do any city driving it drops quickly. On average 50/50 hwy/city I get 15mpg.