DK40 fuel issues

   / DK40 fuel issues #1  


Silver Member
Aug 6, 2007
Spokane, WA
Kubota MX5000 4x4
My buddy has a DK40 with just over 400 hours. He said he was running it this past weekend and ran it really low on fuel. He did not run out but he said there wasn't much left, nor did it sputter. He grabbed 10 gallons of off road diesel, filled up the tractor and then his problems began. He said it was running rough, smoking, and surging from around 700-900 RPM. He changed out the fuel filter, bled the fuel filter housing and injector pump for air. He also treated the fuel for algae and water and added a little cetain boost. He said it will still surge every so often but he did have it running for 45 minutes straight.

Obviously the fuel seems to be the issue. Does anyone know if adding more of the algae/water treatment will further help the possibly bad fuel? He said the tractor isn't running too bad right now but its not perfect. Would that hurt the injectors if he ran this tank of fuel or should he drain it or dilute it with good clean stuff? If he were to drain it, he needs to know what the best way is? If it sounds more like air in the fuel system, would he need to bleed each injector too?

Thanks a lot
   / DK40 fuel issues #2  
Had that happen in my old Kubota. The fuel flowed by gravity thru the flow valve into the fuel bowl before being filtered and picked up by the mechanical pump to the IP. I thought the filter was plugged, changed it
and noticed nothing coming down after opening the valve so I got the vice grips and a rag and clamped the line and took the valve apart. It was amazing what came out. Check the shut off valve--I think you will find
a solid blockage.
   / DK40 fuel issues #3  
New to this thread. I'm having power loss problems with my CK35. Changed fuel filter, had a bit of water in bottom of bowl. Put fuel conditioner in tank and algicide, 1 oz recommended. Still having same problem. Suggestions appreciated.
   / DK40 fuel issues #4  
Check the line from tank to fuel pick-up pump before it goes to the injector.
I pout a fuel filter on mine... after tank - before fuel pick-up pump.
   / DK40 fuel issues #5  
... Does anyone know if adding more of the algae/water treatment will further help the possibly bad fuel? ...

The filter should trap small amounts of water. A biocide should kill the "bugs" (microbes that live at the fuel-water interface). But the dead microbes can plug the filters and other stuff too. Look at the fuel in the tank; is it very dark? If not, you might be able to use an oil sucker to suck water and the worst fuel from the low points in the tank and save most of the fuel. Otherwise, just be sure your lines and filters are clean.
   / DK40 fuel issues #6  
Thought I would follow up about my CK35 power loss problem. After considerabe trial & error trouble shooting, I isolated the problem to the fuel pump. Upon taking the fuel pump apart, found a tiny seed, about the size of a peppercorn, lodged in the injector side outlet. I have installed an inline fuel filter upstream of the fuel tank. Hard to believe Kioti does not include such a fuel filter.
   / DK40 fuel issues #7  
BTW: I was told by the Kioti dealer that algicide products are bad news for injectors -- causing corrosion of them. Anybody heard this story ?
   / DK40 fuel issues #8  
On the old Mercedes Diesels (mine is a 1982), there is a small inline filter just upstream of the lift pump. These are not expensive (like $2-3) and are attached to the flexible rubber hose with hose clamps. The Main filter (officially called the secondary filter) is about the size of a spin-on oil filter and it's located between the lift pump and the injection pump (like the fuel filters on our tractors). Mercedes had a lot of experience with this type of Diesel so I think your proposal to add a prefilter is a good one.