Rollin coal @1800 rpm

[chris142]

I have noticed that my 6.9L will really roll coal @1800 rpm. Is that normal? Is that the rpm where the pump dumps fuel? Anything above or below and it runs reasonably clean

 

[83ford]

Well I know mine being turned way up at lower rpms if I really get on it it just clouds every thing out because it's luggin


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[IDIoit]

i only smoke when i am at a certain load, and i hammer it.( like when the clutch grabs)
what pump?
whats your temps read?

 

[chris142]

Stock pump turned up about 1/2 flat. No other gauges.

 

[Hydro-idi]

Do you have a turbo? If not, you will be smokey with an N/A idi and turned up IP. First thing I would check is the air filter. If it is clogged, replace it and I bet your smoke output will decrease.

 

[IDIoit]

how do you not have a pyro?

 

[chris142]

how do you not have a pyro?

Truck didn't come with one I guess. No turbo.brand new air filter.I change it when my filter minder gets sucked.

 

[Clb]

i only smoke when i am at a certain load, and i hammer it.( like when the clutch grabs)


Rollin coal nope, beautiful haze yep.
Never saw it in a "lug" situation.
If i short shift mine and pin it it will haze up.
You may have a flaky tach sensor also.

 

[IDIoit]

Never saw it in a "lug" situation.
.

or when we advanced it out of the negative. lol

she can be a freight train loaded up.

 

[83ford]

By lug I mean mashin on it and it's dumpin more fuel then what the motor can handle at that rpm.cause mine with accelerat faster at 1/2 throttle better then full cause it lugs it


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[cpdenton]

Pretty sure I read somewhere our db2 pumps deliver the max fueling at or around 1800, then start to defuel above 2200.... I think.

Like I said, trying to remember something I read a while back.

 

[marmot]

Pretty sure I read somewhere our db2 pumps deliver the max fueling at or around 1800, then start to defuel above 2200.... I think.

Like I said, trying to remember something I read a while back.

That is about right IIRC the weights in the governor start moving out on their springs and about 2500rpm start restricting fuel flow. Most diesel engines will smoke when over fueled at low rpm. Even my little 1.9liter "blows coal" if I lug it under heavy fueling, although not near as impressive a cloud as the 7.3's make

 

[Black dawg]

I have noticed that my 6.9L will really roll coal @1800 rpm. Is that normal? Is that the rpm where the pump dumps fuel? Anything above or below and it runs reasonably clean

Timing has as much to do with smoke as fuel rate does, I would bet there is something odd with the timing in your pump at those rpm.

 

[OLDBULL8]

I have noticed that my 6.9L will really roll coal @1800 rpm. Is that normal? Is that the rpm where the pump dumps fuel? Anything above or below and it runs reasonably clean

Your 1800 RPM has nothing to do with ROLLING COAL per se. It's just that you "mashed" the throttle at that RPM and your feeding more fuel than the engine needs, as the RPM's increase, naturally the engine needs more fuel to keep speeding up and the smoke decreases when the level of RPM's is equal to fuel needed. The IP supplies fuel to the injectors to fill the injector for the next injection event thru the return line. the Hi pressure from the IP only triggers the injector to open "and dump it's load", so the more fuel thru the Hi pressure line, the wider/longer opening the pintle is, and feeds more fuel to the precup than it can burn during that stroke, hence the black smoke. Timing of this event in relation to fuel injection and combustion is relevent. Just a simple explanation. Mel would have a more technical explanation.
The IP is always dumping fuel thru the return line, as long as the lift pump is supplying more fuel than the engine is using, that's what helps keep the IP from overheating.

 

[chris142]

Timing has as much to do with smoke as fuel rate does, I would bet there is something odd with the timing in your pump at those rpm.

9° @2000 rpm though