mpg's getting worse

[ms8091]

I know that mpg's will get a little worse in the winter months but I have dropped from say 16-18 in the city to about 13.5 - 14.5. Any ideas, or is this just what I should expect. Will a CAI help or not really. I am running the Diesel Kleen but hasn't helped any.

[ridgerunner98570]

Have you changed all filters? Air filter can be plugged, fuel filter getting dirty etc. Have you changed your tire size or put on more aggressive tread? How much junk you carrying around in the back? Lubed your drive line regularly? Drained the water separator (that's a biggy for fuel mileage) How long has it been sense the last tune up? Do you run injector cleaner (I recommend Power Service Injector Cleaner). What color is your exhaust smoke? Very black could mean injectors need cleaning, white could mean fuel not being burned thoroughly, Blue means burning oil engine wearing out. Hows your tire pressure? Any wobble in the front end , tires wearing the same all around. No alignment problems?

Just before you change your oil, the fuel mileage tends to drop dramatically. More dirt means more friction. More fiction on any of the above means less fuel mileage. It all adds up.

[ms8091]

I just changed the oil/filter and trans fluid/filter. Changed the air filter when I got it 3 months ago. No wobble, clear exhaust, don't know about the injectors but did notice the faint smell of diesel in the engine compartment. The valley seemed a little moist, so maybe a leak? I need to change the fuel filter and I assume when you talk about draining the water separator that's the drain under the fuel filter housing? I use diesel kleen as an additive, everyone seems to like it alot, haven't noticed any difference myself.

[ridgerunner98570]

How moist? The fuel water separator switch on the fuel filter can develop a leak. It leaks down the front of the engine block then onto the ground and that can affect your fuel mileage. Before you buy the "O" ring kit, open and shut the valve a few times to make sure a bit of dirt isn't in there causing the valve to leak. One of the members here sells a kit that takes care of that problem for under ten bucks.

Diesel Kleen is Power Service. Thats what the big PS stands for on the bottle. Good stuff. You need to put in the bottle that says "injector cleaner" and it recomends 1 gallon to 100 gallons fuel. I dump 1/2 gal and then fuel up.then when I use more than 10 gallons diesel, I dump the other 1/2 gal and fuel up again. Takes me from black smoke and injector knock to running clean and smooth.

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Last edited by ridgerunner98570 : 11-06-2009 at 09:45 PM.

[ms8091]

It just started today, leaking down the front of the motor. It looks like the cap might be leaking too. I figured I could do the new filter and replace the orings at the same time. As for injector cleaner, I do use Lucas upper cylinder additive, in addition to DK. Thanks for your help, hopefully this is an easy fix.