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Tom_Barb's avatar
Tom_Barb
Explorer
Dec 18, 2015

Loose Injector

Has any one heard of the Cummins 8.3 ISC having a loose injector causing combustion products to enter the return fuel going back to the main tank and causing the fuel to turn black, then clogging filters when delivered to the engine, on the supply line?

Don't tell me Algae, we know it isn't.

This debris is a fine carbon particles as is found in engine oil and the combustion chamber. (soot) 99% will pass a 10 micron filter, but that 1% will clog a filter every 10k miles.

Things done so far:
tank removed and cleaned, (thinking we got a load of bad fuel.) 10k miles later fuel is black again, and filters clogged.
New filters installed, 12k miles later they are clogged again. fuel is black.
All hoses removed and replaced. tank cleaned again. (10k miles later fuel is black again, and filters clogged)

Engine runs strong, until we get a low fuel pressure light and a code of low fuel pressure. change both the engine and chassis filters ad it will run strong again for 10k+ miles.
This engine will not use 1 qt of oil between 15k mile oil & filter changes.

I'd like to know of any other 8.3 ISC engines that have had a loose injector? this engine has done this since day one mile one. 43k miles later we are still trying to figure out why it will return black fuel to the main tank.