Drastic drop in mileage

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  #1  
Old 01-08-08, 02:44 AM
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Drastic drop in mileage

I have a 2002 f250 powerstroke diesel. It has 86,000 on it. Thus far, the only thing I have done is oil changes, and routine maintenance. It has always run great. However, the fuel economy really dropped off all at once. Like, dramatically. It still runs good though. Could someone give me an idea as to what is causing the sudden drop in mileage?
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Old 01-08-08, 07:26 AM
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I too am looking for help in here , am not a mechanic by trade, but have done more than my share of wrenchin'. Have you changed fuel lately? Possibly getting buildup of Fuel Gel in the fuel lines from diesel fuel. Clean Air Filter? Plugs still in good shape? Maybe not getting quite as hot as need be. Just a couple thoughts for ya. Laters, Syx.
 
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Old 01-08-08, 08:13 AM
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Drastic drop in mileage

How often should you change the glow plugs? What would you use to clean the lines if there is a gel build up?
Thank you
 
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Old 01-08-08, 08:43 AM
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Originally Posted by SyxPak View Post
I too am looking for help in here , am not a mechanic by trade, but have done more than my share of wrenchin'. Have you changed fuel lately? Possibly getting buildup of Fuel Gel in the fuel lines from diesel fuel. Clean Air Filter? Plugs still in good shape? Maybe not getting quite as hot as need be. Just a couple thoughts for ya. Laters, Syx.
to what plugs do you refer? it doesn't have spark plugs and glow plugs have no maintenance interval...just replace when they fail.

also, glow plugs are for starting and won't affect your fuel mileage. air filter is very important tho. gelling in the fuel line...perhaps if it's really cold where you are...and even at that, that would restrict fuel delivery and cause lack of power
 
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Old 01-08-08, 08:50 AM
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I honestly don't have a good answer for ya. I have found where I live, West Central Illinois, Calling a local Dealer and ask to talk to a mechanic, that they have always been friendly and glad to answer a few questions. I would think they could tell you exactly what you need to know. Run the original problem across to them, if possible. Or I'd bet someone in here can give you the info you need.
I don't want to give you bad/wrong advice. I haven't had diesel, but have overheard shop talk about glow plugs and line gel, so I thought I would pass a little along..... Wish I could be of more help, Syx.
 
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Old 01-08-08, 03:03 PM
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I would check the air cleaner first. Are you blowing black smoke regularly of late? Injectors could be clogged from inferior fuel supply. I run a Dodge Ram 24v Turbo, but haven't had a fuel mileage drop like the one you describe. You could have a dealer or shop plug into the diagnostics and see if a code shows up. Only time we had problem with fuel gelling at the Atlanta Airport for ground equipment, we had to dump 500 gallons of Avjet #1 in the underground tank. The fuel gelled in the ground to where the dip stick stood erect when we plunged it in. That's cold.
 
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Old 01-08-08, 10:15 PM
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Powerstroke

I agree with the above, it could definitely be related to air intake, maybe a clogged filter element or some problem with your turbo charger, those Cetane booster they sell at autoparts stores do work also, what kind of mpg are you getting anyways, I drive an '07 duramax 1 ton truck,pulling an enclosed trailer tandem axle and I get 11 mpg consistently, maybe 15 without trailer
 
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Old 01-09-08, 07:40 AM
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the mileage drop was about 1/3 . I was getting about 420 miles per tank and now about 300. I did add a diesel additive to the tank prior to the drop come to think of it. The airfilter has less than 5,000 miles on it. Could the diesel additive had that kind of effect? Thank you
 
  #9  
Old 01-09-08, 11:41 PM
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A Powerstroke injection is a different animal driven by the engine oil. It was a system Ford and International got together on, I believe. Having the correct engine oil and keeping it in good shape is critical for the injection system. I think I would take a look at that end of things.

If the poor mileage just started, it could be the fuel. What was the additive for - cleaning or just a maintenance conditioner? Something like Power Service wouldn't cause a problem.

I would also check the catalytic converter. It should have one.

As already mentioned glow plugs = starting.
 
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Old 01-10-08, 04:28 PM
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You may have some component failure that has put the system in a limp mode. We had that problem with our old UD rollback. Can't remember what we had to do to fix it, but when it was "limping" it really sucked the fuel. You've had it scanned?
 
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