Kubota diesel restart problem

Discussion in 'Heavy Equipment & Pavement' started by squarewheels, Oct 15, 2006.

  1. squarewheels

    squarewheels LawnSite Member
    Messages: 5

    Hi all. I am having an engine restart problem with the 2.2L Kubota diesel in my 7753 Bobcat. Air is entering the injection pump. This occurs when the engine is at full operating temperature and is then shutdown for more than 20 minutes. To restart the engine I must open the bypass valve on the injection pump, and then press the fuel bulb several times. If I do not purge the air, the engine will start for a second or so then die and not restart. The rubber fuel lines are old, not cracked, and do not appear to leak. All hard lines appear to be in good shape. There are no diesel leaks on the outside of the injection pump. Any suggestion as to the cause of this problem is much appreciated.


  2. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Messages: 752

    Could be the check valve in the primer bulb. Recheck all lines and return lines. Could also be a leak in the suction line inside the tank on the pick up.
  3. squarewheels

    squarewheels LawnSite Member
    Messages: 5

    xcopterdoc, thanks for the good suggestions. Will do.
  4. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    Also try replacing your fuel fill cap. I left mine lay one day while fueling and my emplyee picked up a cap in my tool box from a car and put it on. Developed the same problem and had a hell of a time figuring out the problem.
  5. Digdug

    Digdug LawnSite Member
    Messages: 125

    squarewheels- you are losing the prime somewhere. Try spraying starting fluid on all the areas between your injection pump and the end of the hard lines. Do it when the engine is warming up not fully hot, because you say it does it after it cools for 2o mins . I think the leak will be on a metal part somewhere that is tight when the engine is hot and loosens or changes shape as the tempature declines. When the engine revs you have found your air leak. good luck . doug
  6. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    Check all the flare fittings on the steel fuel lines to make sure they are tight.
  7. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Messages: 752

    Any luck yet??
  8. squarewheels

    squarewheels LawnSite Member
    Messages: 5

    No luck yet. Fuel cap appears to be stock, o-ring seal is good, and the vent appears to be working. Hard lines are all tight. Soft lines had no loose clamps. I will replace the soft fuel line from the primer bulb to the injector pump with a clear vinyl line... so I can see if air is being feed to the pump.

    Have not checked the primer bulb to ensure the one way valve is working. I plan to replace it if I see air bubbles appear in the vinyl line after shutdown. As for the primer bulb -- are diesel fuels bulbs and marine (outboard engine) bulbs interchangable? If not, I'll be making a trip to my friendly Bobcat store.

    Again, thanks all for your great support. It is much appreciated.
  9. Gravel Rat

    Gravel Rat LawnSite Fanatic
    Messages: 9,544

    What about the fuel filter it is tight you could be sucking some air or how is the fuel filter when was it changed last ?

    How soft is the fuel lines it possible be once they get warm the suck flat.
  10. squarewheels

    squarewheels LawnSite Member
    Messages: 5

    Hi all,

    A quick update -- I installed a clear vinyl fuel line from the filter to the injection pump. Ran the engine, at idle, for about 30 minutes. No air bubbles in the line while running or after shutdown. No restart problems. Either the problem is fixed or I need to bump the 'cat into some berms to shake things up a bit. I've got a job late next week for the Bobcat. I'll let you if it restarts after a hard day of work.

    As for the fuel filter -- about 2 months old.
    Soft lines -- they do not appear to be collapsing.

    And, I really do appreciate the support I have received -- thanks.



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