kubota engine satrting problems

guyman

New User
The engine will start and run but only in start position and dies when returned to run position. Any suggestions?
 
I believe Kubota Engines have an electric solenoid to turn the fuel off and on. When starting there is 12 volts sent to the solenoid and when it's running there is only 6 volts going to it. So it's 12v pull in and 6 volt hold in. If your solenoid has 3 wires going to it one is the ground and the other two are start and run.
 

The engine is in an asphalt roller. Fuses are good. Fuel pump runs when switch is turned to on. Connections seem to be good.
 
This may not directly apply, but maybe you could use this information and a wiring diagram to find the answer.
Gas vehicle ignition systems used an ignition resistor or a resistive wire to apply 12 volts to the coil during start up and drop to 6 volts during run. They would simply bypass the resistor while cranking and place the resistor in the circuit when the starter was released.
A bad resistor or resistive wire would cause the problem you mention.
If you have a 12/6 volt fuel shutoff solenoid, maybe a similar arrangement is used.
 
newer kubota tractors are equipped with a operator
presence relay that presents the same symptoms when
they go bad and my understanding it is quite often.
not sure if your roller is so equipped. on mine it
was mounted inside the dash right behind the removal
face plate. easy to locate, easy to identify and
easy to replace. $75-$100 at your dealer.
 

The Kubota M4900 tractor I owned had an oil pressure switch that had something to do with the fuel solenoid operating IE no oil pressure no fuel to injectors. Maybe that switch is at fault.
 
Could also be a plugged fuel filter. When there is water in a fuel
filter, there is a gum line that blocks fuel flow, at higher rates. it
will let enough through to run at an idle, but any advance over that,
and it'll die.
 
Well let me wade in. Twenty + years of Kubota experience and there are a lot of pretty good answers already spit out but here is my best guess. The guy that pointed you toward the fuel sonolid was getting you started. TWO different systems used on Kubota engines. ONE as he stated has three wires when you turn the key to START one coil is energized called the PULL in coil then when you release the start key to the run position power is supplied to the other wire called the hold in coil. In your setup IF and I say IF you have a two wire set up the Fuel control relay located somewhere back up in the wiring harness is bad. Going to be an electrical problem.
 

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