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terence6
terence6

Posted: Sun Feb 22, 2009 1:03pm

Post Subject: diesle engine

I have a four cyl kubota engine, the engine rev's increase and decrease normaly when under load. When out of gear the rev's climb gently to about 2000 rpm. When put back under load the rev's fall back to 1000 rpm, the rev's can sometimes be brought down to low idle by blipping the engine. The fault started about 12 months ago appearing very infrequently but now occurs more often. Can anyone give me any idea as to where to start to cure the fault.

Tony-B
Tony-B

Posted: Mon Feb 23, 2009 9:30am

Post Subject: diesle engine

Dear Terry, Sometimes diesels do this when they are suffering from fuel starvation caused by blocked filters or an air leak into the system, but I would not expect it on a Kubota. If it is not that then I suspect the Governor on the injector pump, but first just make sure throttle cable is correctly clamped and fitted at both ends. If its loose I suppose it could allow the throttle lever to open. Change all the filters, including and water traps that may be fitted and empty them into a bowl so you can inspect the contents. Any slime or discoloured diesel may indicate the presence of fuel bug which will need treating. A lot of water indicates the fuel tank needs the water sucking from the lowest point or draining from the drain plug if fitted. Once you have assured yourself there are no air leaks and the fuel supply is in good order I suggest you consult a reputable engineer experienced in Kubota engines to get his views and to see about getting the governor checked.

Tony-B
Tony-B

Posted: Mon Feb 23, 2009 4:45pm

Post Subject: diesle engine

I have been mulling this problem over and I think it would be a very good idea if you ensure the fuel return pipe from injector pump to tank, via the injectors is free of obstructions because if the lift pump managed to "over pressurise" the injector pump when on tick-over the result may well be exactly what you describe. I know the French version of some Kabota engines had a problem on the fuel system related to a rubber elbow, so its worth a look.

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