The last 2 tanks of fuel i've ran through it i've got about 100 miles out of roughly 14 gallons in my back tank. I can't see any leaking fuel. The valley behind the injector pump is wet with a touch of standing fluid but I don't see any leaking out of anything anywhere or dripping off of the truck. I'm wondering if it only leaks under driving conditions when the rpm's are up? I noticed my air filter is dirty but I don't think it would degrade my fuel economy that much! Thanks in advance!

 

Are u buying fuel at the same station all the time. Could be old fuel it station does not pump very much fuel especially with the winter blend. Just a thought.

 

The last 2 tanks i filled up at the same station which is the one usually go to all the time. With the hood up i could smell a slight fuel odor but couldn't see any leaks.

 

I would thoroughly check the fuel pump/fuel filter assembly in the v of the motor again. There are many places it can leak from. Clean everything really well, and then crank the motor, and try to find where the leak is. There's not supposed to be standing fuel back there. This happened to me last year, and it was leaking from a tiny, unused valve on the side of the fuel filter housing. It was slow, but steady.

 

Cool i'll clean is up and check it out again. It just throws me for a loop when I can see it coming out sitting in the driveway ideling or with the high idle on. As bad as my mpg's got I figure you'd see it gushing out. LOL!!!!!

 

This winter fuel get's a lot worse fuel mileage for me. I know that's all it is in my area. Every distributor here has switched to a winter/bio blend. It really hurts. Plus I've not unlocked my hubs since Christmas eve thanks to all the snow, ice and mud. My driveway is a mile long and gravel. Now covered with mud I've tracked in. It's a little slick.

 

I didn't think it would take that big of a hit on my mpg. I was getting about 13 - 14 mpg. With 14 gallons in the back tank at 100 miles thats like 7 mpg!

 

Grrr....i have the same issue. I got 100 miles to my front tank...and when im near the truck you can smell diesel. Cant find any leaks tho.

 

I can only smell it under the hood.

 

Possible causes of the bad mileage

Running with hubs locked
ebpv working. The engine needs it but you really burn some fuel while it is closed.
tire pressure not to what it says on the door sticker
oversized tires
bad alignment
engine mods
potatoes stuffed in the tail pipe. Don't ask.
lead foot
loose nut behind the wheel
leaks
engine temp too low. take off the fan in the winter and/or cover the radiator
ULSD and even more so winter grade ULSD and bio mix
bio diesel in general
brakes dragging from ice
big cow catcher bumpers. I'm guilty of this one but I still average 20 mpg.
doing the current speed limit or above in a truck that was designed for a 55 mph speed limit.
chip that you don't know about on your PCM

 

Pretty good list there.

Fuel fumes are bad, though. Should not be smelling them at all. Diesel, by itself as we know, is not as volatile fuel as gasoline, however it is still a hydrocarbon and can ignite under heat, so you need to track it down. It shouldn't be too tough to follow the lines from the tank up to the front of the vehicle and into the fuel filter, pump, etc. I would consider powerwashing the undercarriage and engine compartment to thoroughly clean everything. Then, let the truck sit for a while to see if a leak develops while the engine is not running and the truck is just sitting there. If nothing, then start the truck and run the same check. Like I mentioned before, the chance of diesel fuel or fuel fumes igniting openly from heat or an exposed electrically operated device is small, but you don't want to take any chances. Just my 0.02 Good luck finding it.

 

You could try looking at the lines that come up the front of the engine. They're steel so the rust before the ss brake lines. I didn't know mine were leaking until I saw that the front end was wet. Just my $.02.

Red

 

I've been getting between 13 and 16 depending on what the temp is around here.

My mileage has imrproved quite a bit lately though. Sounds like you have a leak somwhere. make sure it's not something as simple as the fuel filter not being tightened down properly. I've had that happen to me several times.

Here are the other things I've done that have helped.

fuel filter, air filter, oil change and filter, fpr screen.

the fpr screen was pretty dirty on mine and improved my mileage and smoothed out the idle quite a bit.

I also started running powerservice in the last couple of tanks. It seems to have improved my mileage slightly, but it's hard to tell with the big temperature swings around here.

I've also seen suggestions to fill the fuel bowl with PowerService Diesel Kleen and start her up to get the injectors really nice and clean. I'll probably do that the next time I pull the fuel filter.

 

Good suggestions fellas. I'll give them a try. I just filled up at a different fuel station to see if it was a problem with the fuel it self. I'll check out the fpr screen I've never cleaned it before. It is under the brass bolt? Or is it located somewhere else. I sprayed the motor off yesterday and i'll get the flash light out and see if anything is on there now. Thanks!

 

Remove the cap on the fuel bowl, pull the filter and drain the fuel bowl, Get some carb cleaner and blast out the fpr screen top righ hand side of the fuel bowl. Spray out the bowl with the drain emptu. Remove the FPR and clean it. Dont loose the spring or jack with it. Spray carb cleaner back through the fpr. Pour some deisel in the fuel bowl. Close the drain valve and add some more diesel. Open and close the drain valve a few quick times. Then leave it open a and add a little more diesel. Replace the FRP. Fill the bowl and slowly replace filter. if level get too high, slightly open the drain while pushing the filter down until it seated. Change the filter if needed. Watch for gasket roll when reinstalling the cap.
I have a 3/8's hose on my drain line and have it tye wrapped to the cross member yoke. It makes it nice to drain and check the fuel. If you want to do this lay under the front of your truck and locate the batt wire that is running to the starter just behind the radiator there is a batt cable guide support. Reach over it and you will find the end of the fuel bowl drain line. Attch hose using a small worm gear clamp. I slit the hose slightly on either end and put diesel on the end and used some pliers to push the hose up on to the tube. Its a little troublesome to reach but you will enjoy it later on as it really helps if you have to work on the fuel bowl.
Add a can of sea foam to each tank when filling them to help clean the fuel system out.
There is also a prefilter mesh screen that gets dirty.
FPR shims dont do unless you know your psig before hand.





Item Part Number Description
1 9278 Oil pressure sensor
2 6600 High-pressure oil pump
3 6049 Cylinder head
4 9A332 High-pressure oil feed hoses
5 — High-pressure oil rail
(part of 6049)
6 — Injector oil feed galleries
(part of 6049)
7 9F593 Fuel injectors (8 req'd)
8 9F838 Oil pressure sensor
9 7A139 Injection pressure regulator (IPR)
10 6019 Engine front cover
11 6658 High-pressure oil pump reservoir