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Thread: Any ideas on Kubota D902 engine that won't start at low throttle?

  1. #1
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    Any ideas on Kubota D902 engine that won't start at low throttle?

    I have a 2019 Grasshopper mower with Kubota D902 engine that suddenly won't start at low throttle. I have always started it at the lowest throttle setting and it started just fine. Now, it simply won't start at the lowest throttle setting. I thought something was seriously wrong, and I was just about to start checking for air in the fuel system when I decided to bump up the throttle for some reason and then it started just fine. It runs just fine once started. Should I be replacing the fuel filter to see if that will help? The fuel filter has about 230 hours and five years on it. Other ideas?

  2. #2
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    My first thought was to change the fuel filter before I even got to the part where you mentioned it.

  3. #3
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    Normal service interval for Kubota machines is 300 hours, so it certainly wouldn't hurt you to do a fluid's and filters service "now". You might also physically inspect the throttle control setup to ascertain if something might have "slipped". These engines are nearly "bullet proof" so it's likely "something stupid" that's causing your issue. Some folks with Kubota machines are replacing the small "disposable" fuel filters with larger filters by relocating to a place where it's more accessible. I don't know if that's possible on the Grasshopper mower.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #4
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    Grasshopper installed a larger spin-on type fuel filter a bit bigger than the oil filter instead of the tiny little cartridge filters used on some Kubota engines. I also have a slightly larger Kubota engine powering a generator in my motorhome. It has the tiny little cartridge fuel filter.

  5. #5
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    That's really nice that Grasshopper did that...it's a big miss on so many small diesel machines when the small filters get employed. (And my BX22 has TWO of those little thangs that are very much in inconvenient places) I still think doing a fluid/filter service is a good idea here and if that solves the issue, great. If not, nothing is lost as you move to more detailed diagnosis. If there's a forum site that caters to the brand, it may be good to see if other folks have experienced a similar issue and what solved it.
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    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
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    It sounds like your injectors are getting plugged up a little. I had that happen on my Kabota L225 when I got some bad fuel.

  7. #7
    Maintenance recommendations almost always have an hour, miles, and / or elapsed time suggestion. I don't think the intervals are ever as long as 5 years. I tend to ignore the elapsed time and only pay attention the hours or miles. This is likely not a good policy.
    My only diesel is the 1976 ford. It acts differently with red diesel than it does with yellow diesel.
    Last edited by Maurice Mcmurry; 06-11-2024 at 7:07 PM. Reason: left out a word

  8. #8
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    I am definitely overdue on the fuel filter. I change the oil and filter annually, but things like fuel filters get overlooked. Grasshopper doesn't list any months or years intervals for the fuel filter. I have changed the hydro pump oil and filter.

    Is there anything else that might cause an issue like this?
    Last edited by Brian Elfert; 06-11-2024 at 10:01 AM.

  9. #9
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    Starting and running issues with a diesel are almost always fuel related. If you can drain some of the fuel out of the bottom of the tank to look at in a glass container, do that. Otherwise, just change the filter and see if that solves it. I wouldn't spend any time thinking or worrying about it until a new filter is tried.

  10. #10
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    If you start it at a slightly higher RPM from idle what happens when you reduce it to full idle after it's running and warm? 'Just curious...
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    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
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    My only diesel is the 1976 ford. It acts differently with red diesel than it does with yellow diesel.
    Red diesel is for off road use.

    Yellow diesel is usually diesel that is old.

    On-road diesel is clear or slightly green. Refineries place a green dye into diesel fuel which is obvious if fuel is freshly dispensed into a bottle to observe its color. As fuel ages this dye fades to yellow or darker colors. Part of a visual observation to inspect diesel fuel quality is to check the fuel for a “bright” appearance with the slight green dye being a giveaway that the diesel is fresh and in good condition.
    From > https://staroilco.net/every-question...f-road-diesel/

    My knowledge of working with old diesel fuel in zilch. Following is an experience with a gasoline problem.

    My mower uses gasoline and has set for close to a year, the gas is old. After starting and getting started the engine cut out. For a minute or two, to keep it running the choke and fuel had to be played back and forth. Finally the engine started running with out the jockeying of the fuel to air mixture to keep it running.

    That was my first or second time having a problem with older gasoline. It may have been some moisture in the fuel since it is kept in the greenhouse.

    jtk
    Last edited by Jim Koepke; 06-11-2024 at 9:47 PM. Reason: fixed use of of instead of off
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
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  12. #12
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    Quote Originally Posted by Jim Koepke View Post
    Red diesel is for of road use.

    Yellow diesel is usually diesel that is old.



    From > https://staroilco.net/every-question...f-road-diesel/

    My knowledge of working with old diesel fuel in zilch. Following is an experience with a gasoline problem.

    My mower uses gasoline and has set for close to a year, the gas is old. After starting and getting started the engine cut out. For a minute or two, to keep it running the choke and fuel had to be played back and forth. Finally the engine started running with out the jockeying of the fuel to air mixture to keep it running.

    That was my first or second time having a problem with older gasoline. It may have been some moisture in the fuel since it is kept in the greenhouse.

    jtk
    "Red diesel" is #2 home heating oil which is not subject to federal fuel tax. Makes it easy for inspectors to verify OTR trucks aren't cheating on taxes.

  13. #13
    I am calling highway diesel yellow, it is mostly clear. I keep mine fresh. If I take the long route to the wood lot I can stop for red tractor diesel and save a few dollars. I do think the ford starts easier and smokes less with highway diesel.

  14. #14
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    Red diesel is for Off Highway use and doesn't have the road tax added into it. Something like a $10,000 penalty if caught in a road truck in North Carolina. The red is just dye so the cops can tell the difference. My tractors run with no difference on either. I don't know that there is any difference between home heating oil and diesel. I have a hundred gallon tank that I go to buy offroad diesel in, but if it's empty and I don't have time to go up in Virginia to fill the big tank I just buy some on road diesel from the closest station.

    I did have my truck checked once outside a restaurant. A state trooper walked up and announced he was going to check my truck. When he dribbled some on the side of my truck I politely handed him some paper towels and a spray bottle of Windex and explained that he really should clean that off. He did.

  15. #15
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    Quote Originally Posted by Tom M King View Post
    Starting and running issues with a diesel are almost always fuel related. If you can drain some of the fuel out of the bottom of the tank to look at in a glass container, do that. Otherwise, just change the filter and see if that solves it. I wouldn't spend any time thinking or worrying about it until a new filter is tried.
    It is a plastic tank with no drain. The two hoses go in the top.

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