'09 SuperDuty fuel consumption

[bucket]

I don't know if anyone around here knows anything about the 6.4 diesel, but I'm looking for a little advice. The truck only has a little over 100K on it and it runs fine. It used to get around 13 mpg the way we used it. Then it sat for a while because of a coolant leak and bad thermostat. After eventually replacing the radiator, hoses, and thermostat, the truck's exhaust burns your eyes and it only gets 8 or 9 mpg. My friend said it was burning oil too, but I took it on a 2 hour trip towing about 28K behind the truck and it didn't seem to use a drop of oil.

I'm diesel dumb and don't have the slightest idea of where to start. Is it possibly injectors that need cleaned/replaced, or could it be something more simple?

Also, I'm kinda wondering what the value of the truck might be. It's an '09 F350 crew cab dually 4x4 with a good body and decent interior. Tires are fair, it drives well, 4x4 works good, it has a ranch hand type front bumper and a C&M flatbed with toolboxes and a gooseneck ball. Interior is basic vinyl but has power windows/locks and power heated mirrors. AC blows cold.

 

[Smith]

Id be curious if you have a stuck or leaky injector especially after it has sat and now its giving you this problem. If so Id get this replaced ASAP, a leaky injector washes the cylinder with fuel and will lead to a Kaboom down the road.

 

[Skweegle89]

Sounds like an injector to me.


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[marks86]

Id check out diesel bomber or one of those forums for this type of question

 

[bucket]

I can't remember exactly how long it sat, it was at least a couple months. It started leaking coolant so it was driven sparingly for a couple months and then when it got cold we realized there was no heat so then it didn't get driven at all for a couple more months.

Injectors sound expensive. And if it's like the radiator, hoses, and lower alternator... it's a PITA too, lol.

 

[Skweegle89]

How does it idle cold? Does it smoke more than it did before?


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[bucket]

How does it idle cold? Does it smoke more than it did before?


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We just started it up today, after sitting a couple weeks. It started right up and ran fine. We let it run a couple minutes in the shop and it actually didn't fume us out. It has been getting driven a little more regularly over the last couple months. Maybe it just needs to be driven more often?

 

[Skweegle89]

You might fill it up and run some Lucas injector cleaner through it just to be on the same side.


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[GTME94]

'08 was the first year for DPF - Diesel Particulate Filter which is basically a soot trap in the exhaust. That DPF eventually gets full of soot and the soot needs to be burned out. If the vehicle is driven under heavy loads the exhaust gets hot enough to burn the soot in what's called "passive regeneration" of the DPF. If it is driven lightly or in whatever conditions that make the most soot in the exhaust without getting hot enough it has to go through an "active regeneration" where fuel is injected while the exhaust valve is open so that the fuel goes thru the exhaust and into the DPF and burns the soot.

That active regen uses a lot more fuel while it is happening, makes the exhaust really hot and can really stink and smoke under certain conditions. I don't remember if the cluster gives you a notice that it is going thru regen or not.

That could potentially be the issue.

 

[bucket]

The cluster used to say "drive to clean exhaust" or something like that, and it would say it often. That's when it got good mileage.

These days I haven't noticed it saying that. The truck is used to tow heavy loads at least 50% of the time. Loads are usually in the 15-25K range.

 

[Skweegle89]

Those EGR valves are bad about going out too.


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[Smith]

The cluster used to say "drive to clean exhaust" or something like that, and it would say it often. That's when it got good mileage.

These days I haven't noticed it saying that. The truck is used to tow heavy loads at least 50% of the time. Loads are usually in the 15-25K range.

As was mentioned above about Regen, that is also on the money. Keep in mind that those Powerstrokes also have an oil journal in them that engine oil seems in to lube the injector itself. If oils sits it gets gunky some times, running it and getting it warm may clean some of the gunk out. Also a buddy of mine rebuilds a lot of Powerstrokes and he swears by this stuff called Rev X which is an oil additive. Says it helped his personal Powerstroke that an injector was starting to stick in.

 

[GTME94]

The 6.4L doesn't have the HUI injectors that use oil to power the injectors. The 6.0L and earlier Power Stokes do. 6.4L has a high pressure common rail injection system. The EGR system can get blocked but I don't remember how much that affects fuel economy.