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genset flooding with diesel, tank level

Discussion in 'Technical Discussion' started by Pascal, Apr 30, 2011.

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  1. Pascal, Apr 30, 2011
    #1
    Pascal

    Pascal Senior Member

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    here is an odd one...

    i have two Northern Lights 20KW (7 years old) which runs very well. Recently, on only one of them the crankcase fills with diesel when the tanks are full and fuel level is about 18" above the genset. after a few days, crankcase is completely full.

    the odd thing is that it's only happening on one of them and it never happened in the past.

    I had the injection pump rebuilt and replaced the lift pump, as these are really the only two things that can let fuel in the crankcase. Unit runs fine, holds a load, clean exhaust, etc...

    NL dealer suggests installing solenoids to shut down the fuel supply when genset is off. It makes sense but it feels like a work around.

    i've called NL tech support, someone is supposed to get back to me...

    does anyone know if it's common practice to have solenoids on fuel lines when the genset is below fuel level?
  2. K1W1, Apr 30, 2011
    #2
    K1W1

    K1W1 Senior Member

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    Hi,

    I know of one CAT Dealer who fits them to all Gensets and Main Engines.

    You could eliminate or condemn the lift pump by taking it off and leaving it over a bucket with the supply line connected as normal and see if fuel appears in the bucket.

    If the fuel is leaking when the engine is stopped it will probably also be doing so when it's running.
  3. dennismc, Apr 30, 2011
    #3
    dennismc

    dennismc Senior Member

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    Generator fuel

    I had that happen on an older kohler 20 kw but it had a simms fuel pump and fuel leaked past a seal internally in the pump housing almost caused a runaway..be careful.
    another unlikely scenario is a leaking injector passing fuel on top of the clyinder, some engines have what's called a "jet start cock" which allows full fuels flow to the injectors and return line for quick bleeding of the system, then it is closed off and the injector pump then provides fuel only...not sure about NL..
  4. Jimbo1959, Apr 30, 2011
    #4
    Jimbo1959

    Jimbo1959 Member

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    What about the return line?
  5. Pascal, May 2, 2011
    #5
    Pascal

    Pascal Senior Member

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    Yes both feed and return lines would have to have solenoids since we have a fuel return manifold near the gensets and a foot higher
  6. Pascal, May 2, 2011
    #6
    Pascal

    Pascal Senior Member

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    Talked to NL tech, he agrees solenoids are just a work around and that either the new lift pump is bad or the injection pump was not rebuilt properly

    Got to isolate the problem by pulling them and rigging them so fuel leaks in a bucket... Which i can't do for now since the I m heading north tomorrow...
  7. jhall767, May 2, 2011
    #7
    jhall767

    jhall767 Senior Member

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    Putting the solenoids on would just mask the problem. Plus fuel would be getting into the crankcase when you ran the engine anyway. Chances are you have a problem with either the lift or injection pumps. It wouldn't be the first time a new or rebuilt item came with a defect. I just redid some fuel lines on my engine and there were two pipe fittings that were bad from the start. Had to go buy new ones to fix the leaks. Can you pull the lift pump off the engine and leave the lines connected to see if any fuel is leaking? The injection pump would take a bit more work.

    Edit : Looks like our posts crossed - good luck finding the leak.