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  1. #1
    New Member
    Join Date
    Nov 2011
    Posts
    4
    Tractor
    Kubota B1550 HST

    Default Kubota B1550 HST won't start easy and no trottle control

    Hello Group,

    I have a kubota B1550 HST that I bought supposedly needing a head gasket. Well long story short it was the head itself that was cracked and not just a gasket. Here are the parts I have replaced thus far.

    New parts:

    Air Vent Plug (bleed screw)
    All 3 new fuel lines
    New fuel tree (the part that attaches between all the fuel lines)
    new fuel cutoff solenoid.
    New starter
    All new fuel lines
    Oil and filter changed 3 times to get all the crap out

    I have solved the head problem as now I am not leaking a drop of anti-freeze but it won't start easy and when it does it does not throttle up and down or minimally does so. I did set the valve lash and also disassembled/cleaned the injectors and injection pump side as well. The valve lash I set at I believe .007" as should be within the range per manufacturers specs but the valve lash was opened up with at least a 3 times larger gap before I adjusted them. In short I have to double check this now as it did start up at least before with a larger gap but still did not throttle up/down good.

    I also took up the speed control plate figuring that something may have let go there but no luck. The spring assembly was all attached and in place. I suspected the injection pump or governor. I detached the fuel lines and the pump seems to pump as per normal.

    What I noticed re-assembling the injectors is that there is a washer (that the fuel tree sits on) that spins around with 2 holes (obviously for fuel). Initially while cleaning I noticed is that if you turn these that at one point you can see daylight. I figured that was my problem and set them all so that I could see daylight out of one of the holes and then re-assembled. Still no luck. Short of having a pressure tester or buying all new injectors (which I was going to do next) I read that you need to set the pressure for injectors. I assume that is what these washers do but I do not have a tester to set properly. Is there anything I can try like to set at so many degrees from daylight?

    I also noticed (spraying 50% ether at the lines/connections) that I did get some pinging near the injectors so there is obviously an air leak there. Looking at the female side of the top of the injectors where the fuel line sits may not be completely true. This was also a reason to try to replace the injectors.

    I just want to add that initially I replaced just the head gasket before I knew that the actual head was cracked and this thing did run pretty good and throttled up/down with the throttle control as per normal. The only other possible thing is that before I understood exactly how to re-assemble the parts where the fuel lines go into the injection pump that I probably put too much pressure on one of the fitting assemblies where the lower part of the fuel lines attach to the pump trying to dog it down (before I put the fuel lines on). The parts themselves seem okay but I may have possibly damaged something inside the injection pump itself. I don't think so though because I did test with everything re-assembled and the lines appeared to pump even (123 etc). I never removed the injection pump or shim, just the parts that come out the top between the pump and lines.

    I was going to take it in to a tractor shop. Of the 2 (not close to me), one is backed up 2-3 weeks and the other over a month. Also, no flat rate on guestimating the problem. I am just not a big fan of an open ended bill to ring up as many hours as they want on something that is most likely really simple. At this point I am probably just better off replacing the injectors and the injection pump itself. I would probably get out of that cheaper than an eval! It's just frustrating after this much work, efforts, testing and waiting for parts that I have already installed over the last month.

    It could also be a timing issue but this was running good (minus anti-freeze in the oil/exhaust etc.) before I found the head was cracked.


    I am lost on how to get this running again and feel like I have tried everything. Any suggestions/help greatly appreciated.


    Thanks,

    Art

  2. #2
    New Member
    Join Date
    Nov 2011
    Posts
    4
    Tractor
    Kubota B1550 HST

    Default Re: Kubota B1550 HST won't start easy and no trottle control

    Okay, just dis-assembled the injection pump partially. Not the part where the cam moves everything on the bottom side but the whole top assembly including plunger is out. I think I am on to the problem here and perhaps someone out there can clear things up. If you look down into the pump from the top without the "plunger pump" in you will see a little brass pin that helps line up the plunger pump. This little pin is set into place by the "collar" which is under the surface of the pump as it is mounted. The collar has a straight screw head that where you can set it to move the pump plunger into position. What is troubling me is that there are only 2 adjustments for the outside pump plungers and none for the center plunger. Also, if you look into the hole where the pump plunger is you can see that the hole where you adjust the position of the little brass pin thingy is physically smaller on the center line.

    These pump plungers obviously need to sit exactly in the right spot to pump fuel properly and that is adjusted via the collar. I assume the adjustment is with the screw head exactly horizontal. The problem is that the center of the 3 pump lines does not have this little brass pin guide. Can anyone explain? I assume that maybe I don't need it. Also, one of the collars is missing the small attached shaft that turns the brass pin in place. I will be ordering this part (about $30) tomorrow. At least my hopes are 2 of the 3 injector lines will now work. How can I line up the middle line or does it need to be?

    Also before the plate goes on that locks the 2 collars in place there is a lock washer on mine that keeps each on in place. The lock washer is between the collar and the plate however technical drawings do not show washers there. What gives?

    Anyone who knows these pumps please enlighten me as this is what I think the final problem is (not getting fuel). If anyone has a pump out or photos of the collar or this brass pin in all 3 lines would help. I will try to post some photos or links myself.

    Drawings of what I am talking about are here:

    Parts for Kubota B1750HST-D

    Thanks,

    Art

  3. #3
    New Member
    Join Date
    Nov 2011
    Posts
    4
    Tractor
    Kubota B1550 HST

    Default Re: Kubota B1550 HST won't start easy and no trottle control

    Okay, just dis-assembled the injection pump partially. Not the part where the cam moves everything on the bottom side but the whole top assembly including plunger is out. I think I am on to the problem here and perhaps someone out there can clear things up. If you look down into the pump from the top without the "plunger pump" in you will see a little tit (sorry) that helps line up the plunger pump. This little tit is set into place by the "collar" which is under the surface of the pump as it is mounted. What is troubling me is that there are only 2 adjustments for the outside pump plungers and none for the center plunger. Also if you look into the hole where the pump plunger is you can see that the hole where you adjust the position of the little tit thingy is physically smaller on the center line.

    These pump plungers obviously need to sit exactly in the right spot to pump fuel properly and that is adjusted via the collar. The problem is that the center of the 3 pump lines does not have this little tit guide. Can anyone explain? I assume that maybe I don't need it. Also, one of the collars is missing the small attached shaft that turns the tit in place. I will be ordering this part so at least my hopes are 2 of the 3 injector lines will now work. How can I line up the middle line?

    Also before the plate goes on that locks the collar in place there is a lock washer on mine that keeps it there between the collar and the plate however technical drawings do not show washers there. What gives?

    Anyone who knows these pumps please enlighten me as this is what I think the final problem is. If anyone has a pump out or photos of the collar or tit in all 3 lines would help. I will try to post some photos myself.

  4. #4
    Veteran Member alchemysa's Avatar
    Join Date
    Oct 2006
    Posts
    1,290
    Location
    South Australia
    Tractor
    Kubota B1550HSD

    Default Re: Kubota B1550 HST won't start easy and no trottle control

    You might find some useful free info here. Don't overlook the 'engines' folder. Kubotabooks.com
    .

    TIME IS RUTHLESS.

  5. #5
    New Member
    Join Date
    Nov 2011
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    Tractor
    Kubota B1550 HST

    Default Re: Kubota B1550 HST won't start easy and no trottle control

    Yes, thanks for that. I do own a service manual but it is limited for more detail on the actual pump. Also, I have the PDF (that is included in the link previous) that is also limited. I really think that it is the pump. If I had to speculate I would think that I will at least get 2 of the 3 injectors working. I don't see how I can get the center one working without some kind of guide pin like the outside ones.

    Art

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