Kohler 12.5KW Generator Starts Then Dies

[Twins]

Our Kohler 12.5KW diesel gen has always run great until now. It will take a long time to start than will run for a while about 5min and quits. It sounded like fuel problem and I replaced all filters but that didn't help. Could I have sludge in the tank? The motorhome engine starts & runs just fine. Any Ideas?

[The Newell]

did you run fuel low, or did you run OUT? Running a diesel OUT of fuel is a bad idea. They are not like gas engines, as the fuel pump and injector(s) are at least partially lubed by fuel, and can be damaged if run dry.
When you changed the fuel filter, are you sure you got all the air out of the fuel system? The start hard, run 5 minutes, and quit, sounds like there's still air in there. It sounds like that air is preventing the fueling system from picking enough fuel up out of the tank to keep the filter full, then you get a slug of air, and it shuts down. When you changed filters, are you sure you got it back together air-tight?

[GringoPhil]

Sometimes the fuel line itself becomes clogged with gunk and needs a good cleaning and or changed.

[77newell]

If it runs longer after changing filters then it very well could be gunk in the tank.

You didn't mention if it restarts the same after it quits. Does it just suddenly quit or does it gradually die. All a diesel needs is air, compression and fuel. My thoughts and that of the other posters is that fuel is going away. A restriction in the fuel supply would tend to make the engine more gradually die and perhaps sputter on the way there. If the safety shutdowns are triggering it I would expect the shutdown to be sudden and complete. It may help to extend the generator so you can see the shutdown solenoid and see if it moves the shutdown control rod at the instant the engine quits.

Did the hard starting begin at the same time as the sudden shutdown?

All the questions when answered help lead to the likely source of the problem.

[Gimpy]

How much fuel is currently in your tank? Usually have issues around a 1/4 tank or less when trying to use your generator.