Black Smoke?

[JamesG161]

I would suggest Black is an Oxygen starved burn. I know of no Blue solids produced in Combustion.

What burns?
Any hydrocarbon fed to the diesel engine.
Potential Hydrocarbons...
1) No 2 fuel oil sometimes called Diesel fuel
2) Lubricating Oil
3) Algae or CRITTERS per other posts.
4) Tank bottom Sludge?

The only time I see any smoke...
1) Cold start
2) Rapid large changes in engine RPM
3) WOT for the first time in a season

What is exhaust "smoke'?
If not water vapor, small particles of solids.
______
If after a rapid drop in RPM [3000 to 2000], say 1 minute, you still have Black smoke then you have a Fuel/Air mixture problem.
But yours went away. Suggesting tank sludge burn.

Most diesel engines "smoke", slightly, from rapid changes in RPM.
Jim...

 

[JamesG161]

Black smoke means no new Pope, yet.

I lived in Mexico when "The Pope" visited Mexico for the first time. The entire country was in celebration!
Spanish lesson...
Papá = father = pa PAH with the accent mark over the "á"
El Papá = head father in a family.
papa = potato = pah pah
No accent mark over the last "a"
______
The Pope is...
El Papa.
I looked at my Mexican friends and remarked...
El Papa = The head Potato?

They had a very long stunned pause, not realizing I was right. They got a big grin and said they had never thought about that.
Jim...

 

[Kermit]

I lived in Mexico when "The Pope" visited Mexico for the first time. The entire country was in celebration!
Spanish lesson...
Papá = father = pa PAH with the accent mark over the "á"
El Papá = head father in a family.
papa = potato = pah pah
No accent mark over the last "a"
______
The Pope is...
El Papa.
I looked at my Mexican friends and remarked...
El Papa = The head Potato?

They had a very long stunned pause, not realizing I was right. They got a big grin and said they had never thought about that.
Jim...

Sounds like a new outfit for Mr. Potato Head!

 

[pateco]

But yours went away. Suggesting tank sludge burn.Jim...

Do any of the additives BioBor, Bioguard, Startron, Seafoam, do anything to remove the sludge, or do they just prevent new sludge formation?

 

[JamesG161]

do they just prevent new sludge formation?

Yes, if used regularly.
Sludge is dead algae [really bacteria or CRITTERS] and their biological discharge from eating the diesel, and perhaps crappy diesel paraffins [like candle wax].
My preferred fuel source has Algaecide[Crittercides] in it, from their suppliers.

There are many posts on "fuel tank" cleaning. My preference is carrying extra 5 fuel filter cartridges and keeping my Wema fuel instrument calibrated and verified. My calibration says in need 10 gallons now, when I fill my tank on Saturday, I will verify calibration on my level gauge again.
Since my Wema gauge is ±5 gallons, I will slow fill the last few gallons.
Jim...

 

[pateco]

My calibration says in need 10 gallons now, when I fill my tank on Saturday, I will verify calibration on my level gauge again.
Since my Wema gauge is ±5 gallons, I will slow fill the last few gallons.
Jim...

I think that is the issue with my fuel gauge. Since I only have a 10 gallon tank, it reads ≈ 1/4 full when it is empty. A new gauge and sender has been on my to-do list for a while.

 

[JamesG161]

My Wema sensor and it works very well.
http://www.wemausa.com/sensors/level-FuelWater.shtml#.WvWufC-ZNTY
The micro switch spacing is the "precision". Mine is 22" in a weird shaped tank.
I trust mine but back it up with Engine log hours. I also carry 2 times my precision in Jerry cans aboard or 10 gallons. I avoid the "sludge" potential bottom except in emergencies.

I had my boat delivered and the Master Captain had to motor sail in 8 foot seas, which stirred up the PO's sludge.
I clogged a fuel filter almost immediately on first motoring. Totally Black!
Not fun.
Jim...

 

[dlochner]

Sludge is dead algae and their biological discharge from eating the diesel

Algae in diesel fuel is a common myth. Algae are green plants that need sunlight to grow and prosper. Most diesels tanks are quite dark and unsuitable for Algae growth. https://en.wikipedia.org/wiki/Algae

There are however a host of other critters that can survive in diesel tanks especially in the interface between moisture at the bottom of the tank and the fuel. Their dead little bodies do form a sludge that can clog up filters.

 

[JamesG161]

Thanks for your Green correction, so lets say "critters" or bacteria that is referred by the diesel suppliers as Algaecides.
Ok "Crittercides" will kill them critters.
Jim...

PS: My previous posts on this thread corrected.