# Kubota M7040SUHD Running Rough



## qcfarms (Dec 14, 2014)

I've got a M7040 with 1600 hours on it and it started running rough. I thought maybe there was water in the fuel so I drained the water separator, put in a new screen filter as well, put on a new fuel filter, and drained the fuel tank just for good measure. Went back out to the field this afternoon and all seemed fine but then it started acting up again. Reading the manual, there could be air in the line so I will try to purge the fuel system of air in the morning. That said, when i do start the tractor, i notice that the fuel level in the fuel separator will fluctuate and it looks like there are air bubbles as the fuel flows into the separator. I would think that the fuel separator should be full of fuel at all times whether at idle or at full power. I was just wondering if any of you Kubota owners have had this issue. I did talk to the dealership and they think it is water in the fuel but they are looking at two weeks just to get to work on it. Being 1 tractor deep i would like to fix it If I can since I'm trying to get a field ready for alfalfa.


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## JD3430 (Jan 1, 2012)

Had similar problems. Get ready to install another filter and keep draining water from the separator.


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## Tx Jim (Jun 30, 2014)

Do you see any water in water separater bowl?? Is fuel tank venting? Have you ever had the cyl head valves clearance checked?


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## qcfarms (Dec 14, 2014)

I did see some water in the separator bowl but since i made the filter change there is not water in the bowl. Not sure if the fuel tank is venting. I will pull the cap off tomorrow and see if that makes a difference. I have not had the head valves clearance....if that is the problem then off to the dealer for a fix.

As far as fuel flow, from what I can tell there is a fuel pump on the side of the engine block. It looks like one hose comes from the tank and the other goes to the fuel/water separator. From the separator it goes to the input side of the fuel filter and from there I guess it makes its way to the injectors. What continues to stump me is the fact that I can watch the fuel flow into the separator when the engine is running. It's like it is not getting enough fuel out of the fuel pump to keep the separator bulb full of diesel. I will start trouble shooting early in the morning......if I can't fix then off to the dealer. Thanks for all the inputs!


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## JMT (Aug 10, 2013)

My m120 had similar symptoms. Problem turned out to be a blockage in the ports going into or out of the fuel separator. Has happened twice to me. Both times there was a bug or spider caught in there guess they are crawling up into my bulk fuel tank nozzle or my transfer tank.

Just remove the ports and make sure they are clear.


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## hog987 (Apr 5, 2011)

Neighbor had a problem with his case tractor every once in awhile ran rough. No power etc. It would run fine for days and all of a sudden want to quite. Turned out there was a little piece of rubber floating around in the fuel tank and every so often it would cover the fuel outlet.


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## Nate926 (Apr 6, 2014)

Sounds like a blockage from the tank to the fuel separator, my fuel separator is full at all times on my m110x. I have had this problem before. I fixed it by taking the hose off where it connects to the bottom of the fuel pump and blowing it out with a air nossel.


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## qcfarms (Dec 14, 2014)

Thanks again to all who replied. As you can tell from the pic, grass was the culprit. Now the real question is how did the grass get in the tank. I am guessing that it may have occurred when I lost my fuel tank cap while cutting hay last year. Runs great now that the grass is out of the way!


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## broadriverhay (Jun 13, 2014)

Good catch qcfarms. Its the little things that will kick your butt.


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## JMT (Aug 10, 2013)

Neighbor of mine had a row crop tractor that was not getting fuel. They could not figure it out until they found a T-shirt in the tank. They thought it was vandals.


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## Orchard6 (Apr 30, 2014)

We lost a fuel cap on a jd 6420 once in the orchard and ended up with a couple of leaves in the tank that would plug up the pick up then float away once the tractor was shut off. I pulled the sending unit 3 times before I finally got the leaves out!


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