RTV 900 Diesel Question

[chado613]

Occasionally when starting the (diesel)kubota, It will start and rev extremely high right away and shut itself off when cold. It will then have to sit for a bit then will usually start right up.

I replaced the fuel filter on the weekend and I went out to start it up this morning, the following happened:
1. Glow the plugs for 25 seconds
2. Started it up
3. Began revving higher and higher
4. Tons of dark grey smoke was coming out of the exhaust
5. I turned the key to the off position
6. The engine kept running hard even with the key off
7. eventually after 20-30 seconds it began to rev down and shut it self off

This only happens when starting the machine cold, It does have a block heater and if plugged it starts fine. Last winter though the machine never did this. I am worried this will lead to a future (larger) problem(s).

I am not sure what the heck is going on here and if anyone has had previous experience with something like this I would love to hear from them.

 

[mickeyd]

Welcome to the site from Alabama. Did you do a search for this problem?

 

[ShaunRH]

Sounds like a fuel problem. Maybe a sticky solenoid or fuel pump control system.

My wife wants an RTV900 badly, so I'm interested in the resolution to the issue.

 

[North Idaho Wolfman]

You have leaking Injectors, and /or plugged fuel return lines.
Pull them all out replace or rebuild them, You could have them tested just to verify that is what is going on with it.
Clean and verify that the return fuel line is not blocked.

 

[kuboman]

Sounds like the fuel rack is sticking. How many hours on the machine? Going to high revs after starting indicates the fuel rack is not returning to idle after starting. The fuel rack is at max for starting and then is suppose to return to idle. Yours is not till it warms up. Has the oil been changed?

 

[chado613]

A comment from a diffrent fourm was given:
"Your problem is related to condensation and moisture around the injection pump not moisture in the fuel. The governor linkage is freezing due to this moisture resulting in the fuel rack lockup at startup. The governor linkage is lubricated by the engine oil. You have moisture in the oil around the engine pump cavity of the block. You need to get that moisture out of the area."

This seems the most likely due to the fact that when I plug in the block heater it starts fine.

Would an oil change help resolve this?

 

[chado613]

The machine has about 250-300 hours on it

 

[Bulldog]

Have you used any fuel conditioner?

 

[chado613]

Yes I have been. I just purchased some diesel 911 which I am going to try as well.

 

[North Idaho Wolfman]

I should have asked hours, leaking injector with that low of hours wouldn't make sense, so I retract that thought.
I would still check the return fuel line for blockage.

If there is moisture inside the engine I would check the valve cover breather, if it's plugged or restricted that would cause issues.
That engines breather setup is a little different than the tractors breather setup, instead of the crank case having a fee flow of air out of the valve cover to get rid of excess gases and moisture it uses a valve.
That valve have been giving all Kubotas fits with the cold weather.
They are freezing closed and causing many an issue.
I would pull it and check/replace it.
Check with your local dealer as some are even under an update/recall status.

Changing the oil will help if there is moisture in it, but it's not going to eliminate the problem, fixing the breather will fix the problem.

 

[chado613]

Awesome! Thanks Wolfman and all others that provided suggestions

 

[ShaunRH]

That's basically just a PCV valve isn't it?