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John Deere 750J

Discussion in 'Dozers' started by Reuben, Sep 19, 2015.

  1. Reuben

    Reuben Senior Member

    Joined:
    Jan 28, 2008
    Messages:
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    Location:
    north central pa
    I got a bad batch of fuel and had to change the fuel filters on my Deere 750J. I operated it for one day and it ran great but I noticed at the end of the day when I was letting it cool down the engine was fluctuating...of sorts. The RPM's weren't necessarily changing, it was just sort of "diesel pinging" and the exhaust note was changing, almost like a echoing affect, (hope you can follow me here). It was doing this about every second. I loaded it up on the lowboy the next day and it was doing the same. I brought it back to the shop parked it for five days until today when I thought it would be best to change the filters again before I start it. After I changed the filters I let it idle for 5 minutes. After five minutes, (of smooth idling I may add),I went to move it and it would not rev past 1200 rpms. At 1200 rpms it would start sputtering like it was starving for fuel, and puffing whitish smoke. I let it sit for a few hours and now it will rev just fine but it is doing the fluctuating "diesel pinging" thing at idle again. Does anyone have any idea what is going on. Fuel issue? injector issue? pump? etc?.
     
    Last edited: Sep 19, 2015
  2. RonG

    RonG Charter Member

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    heavy equipment operator
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    Meriden ct
    I am sure that you will get some better answers but those fuel systems generally have a strainer in the elbow/banjo fitting going in to the injection pump that should be inspected in your search for a cure.Ron G
     
    Last edited: Sep 19, 2015
  3. lantraxco

    lantraxco Senior Member

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    Elsewhen
    Are you getting good fuel flow? I guess I should ask, is this an early one with the usual Stanadyne pump, or is it new enough it's common rail?

    There's a suction strainer in the tank, shutoff valve, transfer pump, any of those can get gunked up if there's debris in the tank. If you got water in the fuel that can affect the injectors if any gets through the filters, and some will.