I've owned my 6.0 for a little over 1,000 miles now and have spent a while around them so i wasn't too worried about buying it from a dealer that warranties it. Ive owned a 6.9 and 7.3s before and got around 20 mpg. It was getting around 14-15 at the start which i wasnt thrilled with but the drank 30 gallons in 120 miles. No smoke, minimal idling no fuel on the ground at work or at home, oil doesnt look to high. Coolant is at the right level. Does anybody have any other ideas of why this 6.0 would go through that much fuel in that short of time?

edit: also should mention it has had a couple times where it tried to start, shuddered and died. that day it took a tap of the pedal to get it to run

 

take out dipstick and smell for fuel... if it isn't leaking externally, it must be leaking internally.... don't drive it long this way or you will hurt an injector or something else. Possible rail leak, injector leak... thoroughly check all the lines regardless of seeing nothing on the ground. TOUCH - for wet spots and along lines, SMELL -try and play bloodhound, and LOOK for wet spots and verify what the fluid is.

It is obvious you are losing fuel. depending on yr and mods done, should get 18mpg min I believe. Keep in mind 6.0's aren't known for economical fuel consumption -rather for their power.

 

only thing on this truck thats not stock is a banks exhaust. i have nothing on the ground at all. i'll have to get that dipstick out again tonight. oddly i've had a lot of tractors come through with fuel in the oil so i'm ready for it. now i just have to get a foot of snow off the hood

 

I see..... then with mods you should definitely see better fuel economy (mid 20's). With EGR deletes, etc.... should include bypass oil filter and coolant filter as a part of your mods...Oh, and some type of reader like ScanGauge (to get familiar with some of your normal readings -and will pay off when sensors are involved in diagnosing). This 6.0 will LOVE you for it and prove so through your wallet.

I hear ya on the stupid snow..... ugh! my least favorite time of year due to that white stuff....

 

are you sure you weren't siphoned? or its the fuel guage? do you have duel tanks?

 

^1+ good input there... esp on gauge functionality

 

i have a 60 gallon in the bed. i wasn't siphoned, theres a hard cover on the bed that locks to the tailgate and it's been locked, my gauge is pretty slow but i started with a full tank, got about 13 (same as standard tank) up until 3/4 when my 120 miles took me to 1/4 tank which is 30 gallons. the fuel had been in there for a couple weeks and when i switched it went a little past full so it didnt leak out. the dipstick didn't smell at all of fuel. if i keep it i'm definitely gonna mod it but the egr has to stay. i'll probably go bulletproof on that. does unplugging it help fuel economy on these trucks?

 

yes it does.... EGR can be kept with Sinister delete is fine...EGR cooler stays in place just gets capped and instead of removing EGR valve and capping off, leave it. I have seen more savings in summer rather than winter, but it does improve.

Wow...I'm kinda baffled on your fuel issue I have to admit. It must be leaking somewhere. Now you are only 4 miles to gal???

Have you done any of the fuel filter servicing? 2 filters on these. In 1000miles to go from 15mpg to 4mpg is insane

 

Where is the second? I remember the screen type from an international 4300 vt365 on that it was on the passenger frame rail. Main filter was done by the dealer about 10k ago


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yes you are right on the international having one there and the other sits on top right front of engine. I believe internationals and F450's -F750's all have that one on passenger side rail and are a cupped screen.

On most smaller F-series trucks the fuel/water remover type filter is along rail on driver's side and again with the other sitting on engine. Both of these filters are better quality cylindrical fiber vs screen type mentioned above.

Filters usually comes in a kit with both and all o-rings.

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Another idea is to also check for fuel in coolant... look for degas bottle swelling. Easy enough to detect diesel in just about any fluid. If you do find fuel in cooling system, take it back to dealer. Big enough repairs.... such as possible injector cup failure or head gasket....