04.5 Fuel smell while idling, terrible mileage??

iker42

iker42

Hmm...
Joined
Aug 26, 2007
Messages
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So I have two issues, both started up at about the same time. My mileage plummeted in November or so down to 11-12mpg or even lower, much more than just a winter fuel drop. Also I have a raw diesel odor that comes on REALLY strong when I idle the truck with the heat on. You can smell it from the exterior of the truck, but it's REALLY noticeable inside the cabin. I've checked the motor and cannot find any obvious leaks. I sprayed down any damp spots that even looked suspicious with break cleaner and wiped them clean, but have yet to find a leak.

Anyone have thoughts to what is causing my issues? Truck runs fine, no excess smoke, no fuel in my oil. Any way they are connected??

*Edit - Smell also dissipates completely when I start driving comes back again after 5 or so minutes of idling.

Mike
 
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I had this problem before and it was the rail supply line leaking. It wasn't leaking enough to leave a puddle or noticeable drops, but enough to smell it.

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randal07 said:
I had this problem before and it was the rail supply line leaking. It wasn't leaking enough to leave a puddle or noticeable drops, but enough to smell it.

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I will take a look tomorrow, we did have all of the lines off the rail last summer, and I hadn't been using the heat until I noticed the problem (or idling the truck really). Could prove to be the issue.
 
Like I said though, it was a small leak, just enough to get the pump a little wet.

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randal07 said:
Like I said though, it was a small leak, just enough to get the pump a little wet.

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Yeah, the pump was damp when I cleaned it with BC, I never actually cleaned it off after removing lines late last year so I always assumed thats what it was from. So I will know for sure tomorrow if any has dripped onto it.
 
Check the #4 injector line also, they are very common for breaking.
 
after cleaning it, did ya get out and romp on it a bit? could be a high pressure leak, my line coming from my top pump was leaking last year, but only above 20kpsi. But then it leaked a lot, making it hard to locate the leak. Zip tied some paper towels over the suspected sources of the leak, romped on it, and sure enough, the towel over the connection to the top pump was wet. You not smelling it other than idling was most likely due to air flow under the hood taking the smell away.
 
Smells like fuel from the tail pipe? Bad mileage is number one sign of a bad injector dumping fuel! If you drive it better buy a rebuild kit the pistons tend to melt before you know something is wrong! The CR is great for compensating for a bad hole to keep the truck running smoothly!
 
dangerous06 said:
Smells like fuel from the tail pipe? Bad mileage is number one sign of a bad injector dumping fuel! If you drive it better buy a rebuild kit the pistons tend to melt before you know something is wrong! The CR is great for compensating for a bad hole to keep the truck running smoothly!
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Uh no. Smells like raw fuel in the cab....

So I checked the rail supply as well as all injector lines and they were all right tight. I will try to get it in to the shop I guess and take the intake off so I can get at everything to remove and reinstall. Probably will do a fuel filter at the same time and check the lift pump for leaks (Installed at the end of march last year)

Scratching my head on this, I rubbed my fingers on every line and connection, none of them left a fuel smell on my hand. Only other option could be the return on the back of the head, but I didn't reach back to check that yet.
 
Run the engine with the fca unplugged that makes it pump high fuel pressure might be able to find a leak that way but don't stick your fingers around anything unless ya don't want your fingers anymore.
 
do you have an aftermarket lift pump on there? what is the filtration setup? could you be pushing fuel past a filter at idle, but when demanding fuel not pushing it past the filter or supply line somewhere? Come on Mike, not that cold out, lets get this figured out or we will have to give it a look in Dillsburg in a couple weeks.
 
I had the exact same issue you've got but mine popped up after I did my injectors. Turns out I had a couple lines not torqued enough feeding the cross over tubes. No leak until the pressures reached about 10k psi. You could only smell it at idle with the vent on. Highway speeds removed the smell. I could only see a slight dampness on the intake side of the head.

Now if you have excessive fuel return to the tank from a bad injector it could very well be leaking from the banjo at the back of the head. It's a pain to get at but it's very doable.

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mikmaze said:
do you have an aftermarket lift pump on there? what is the filtration setup? could you be pushing fuel past a filter at idle, but when demanding fuel not pushing it past the filter or supply line somewhere? Come on Mike, not that cold out, lets get this figured out or we will have to give it a look in Dillsburg in a couple weeks.
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Haha, I moved to Minnesota last year Bro!!! Much colder than PA!

TX_5.9 said:
I had the exact same issue you've got but mine popped up after I did my injectors. Turns out I had a couple lines not torqued enough feeding the cross over tubes. No leak until the pressures reached about 10k psi. You could only smell it at idle with the vent on. Highway speeds removed the smell. I could only see a slight dampness on the intake side of the head.

Now if you have excessive fuel return to the tank from a bad injector it could very well be leaking from the banjo at the back of the head. It's a pain to get at but it's very doable.

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Injectors are worn but not bad, we flow tested them last year diagnosing another issue. We never touched the crosstubes, so I don't think it's that, but I did pop the return on the back of the head to check for flow back, Didn't have any but could be source of odor?? Did you mileage tank when all of this was occurring?
 
It did head south a bit when they started failing but I could still get about 16 mpg highway with them. With my flux II's I couldn't believe I actually got right at 20 mpg hand calculated highway miles. I was quite impressed with that given my truck with me in it weighs 8k lbs.

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Still have the issue. I have unplugged the FCA and found no obvious leaks. I changed all washers on the CP3 to ensure they weren't leaking. Only got about 300 miles to the last tank of fuel with mixed towing, which is WAY below old levels.

Grasping at straws here. One note, when I unplugged the FCA, there was a squeaking that I don't remember from past fca unpluggings. I do know that my mileage has gone down since I switched to this CP3 (a used cp3 used to replace a dead one) But it was never as low as it is now.

What in changing the cp3 would cause a decrease in mileage? The pump should have nothing to do with efficiency, correct?
 
If it can't build enough pressure you won't atomize the fuel adequately and fuel mileage could suffer from that........can you verify RP? Other than that, you're probably looking at injectors.
 
TX_5.9 said:
If it can't build enough pressure you won't atomize the fuel adequately and fuel mileage could suffer from that........can you verify RP? Other than that, you're probably looking at injectors.
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Can not verify pressure, but the truck runs perfect, starts normally everytime, no smoke, gets up and goes on the highway when I want it too.
 
Mine would do the same but mileage dropped quite a bit. All my pressures were within reason too.......I guess the 300,000 miles and the overall hours is what snuffed my stix.
 
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