M9000 injection pump shut off solenoids vibrates.

[BJW]

M9000 with cab, mechanical shuttle.
When preheating before starting, the injection pump solenoid vibrates generating a lot of noise.
Turn key to start, and starter engages and engine starts ok and stays running.
What can be causing the shut off solenoid to vibrate when preheating?

 

[BJW]

I have changed the yellow diode under the dash.
Still have the same problem.
Found out if I disconnect the wire from the engine oil pressure sending unit, chatter problem goes away and everything works as it should.
Any ideas why this would be happening?

 

[Russell King]

I don’t know exactly what is going on but it sounds like that shut down solenoid is actually a “let it run” solenoid. It may be that there are really two solenoids in the case, one to pull the rod in and then one that holds it in. There is some contact inside the solenoid that turns the pull in coil off and turn the hold coil on. I assume that the solenoid is pulling in but the hold coil does not hold and then the pull in coil activates again and again and…

You can probably bench test the solenoid and see how it is operating.

The oil pressure wire may be signaling the engine to shut down due to low oil pressure, but I don’t think Kubota has that type of protection on their larger engines.

 

[007kubotaguy]

I have two M8200 doing the same thing. Basically the same tractor is the m9000. Have not got back to them to check them again but they both have new solenoids. Did not solve the issue.

 

[BJW]

I have changed the yellow diode under the dash.
Still have the same problem.
Found out if I disconnect the wire from the engine oil pressure sending unit, chatter problem goes away and everything works as it should.
Any ideas why this would be happening?

The more I read about this, it sounds like a diode has failed.
Found a large yellow and a small black one under the dash panel.
This is a cab tractor.
Does anyone know the location of another diode?
Parts call for two of the yellow ones

 

[akcooper9]

The more I read about this, it sounds like a diode has failed.
Found a large yellow and a small black one under the dash panel.
This is a cab tractor.
Does anyone know the location of another diode?
Parts call for two of the yellow ones

The other one is by the alternator.