Kubota B3030 Loses power randomly, quits then restarts just fine

[bear15]

We have a Kubota B3030 diesel and it loses power, sometimes quits (continues going if I take foot off accelerator), but restarts just fine. It will go long stretches of time working just fine as normal, but then the problem occurs randomly. We have completed the following. Any suggestion appreciated.
-drained and cleaned fuel tank and fuel lines
-replaced fuel filter & fuel filter cup
-treated fresh fuel, good quality (works on our other diesel engines just fine), added fuel treatment
-replaced air filter

 

[Russell King]

You may need to look into the way the tractor engine stops. There is probably some sort of solenoid that controls the fuel. Some hold the fuel on when running, some shut the fuel of. Both will stop the engine when key or safety switches send signal that engine needs to stop running.

Since you say it will continue to run if you release the “accelerator” I think the operator presence sensor is not working properly. That is some type of switch under or in (or both) that tells the tractor no one is in the operation seat so it shuts down.

That may be cutting fuel flow (on,off,on) and causing issues.

Good luck.

 

[North Idaho Wolfman]

Like Russell said look at the HST switch, the stop solenoid, and the OCP.

 

[bear15]

We have a Kubota B3030 diesel and it loses power, sometimes quits (continues going if I take foot off accelerator), but restarts just fine. It will go long stretches of time working just fine as normal, but then the problem occurs randomly. We have completed the following. Any suggestion appreciated.
-drained and cleaned fuel tank and fuel lines
-replaced fuel filter & fuel filter cup
-treated fresh fuel, good quality (works on our other diesel engines just fine), added fuel treatment
-replaced air filter

Many thanks! We will give that a try.

 

[bear15]

Well, we checked the HST switch, the stop solenoid, and the OCP and they seem to be working fine. Any other suggestions?

 

[North Idaho Wolfman]

Bottle feed the injection pump directly to eliminate any fuel delivery issues.

 

[old and tired]

The OPS operator presence sensor (safety switch) could be working properly but your shifting weight or not having enough weight in the "correct" spot on the seat could still be the cause.

The OPS will not kill the engine if you are not pressing the accelerator.

I zipped tied my safety switch down in the correct position, I haven't had any more shut downs.... Is that safe, heck no but it's less aggravating.

 

[bear15]

Bottle feed the injection pump directly to eliminate any fuel delivery issues.

Bottle feed the injection pump directly to eliminate any fuel delivery issues.

I am not sure how we would do this because it will go long stretches of time working just fine as normal, but then the problem occurs randomly.

 

[North Idaho Wolfman]

I am not sure how we would do this because it will go long stretches of time working just fine as normal, but then the problem occurs randomly.

Reading back through your symptoms I would be looking at stop solenoid and or wiring.
Real simple, remove the wire that goes to the stop solenoid while the engine is running.
If it stops running when you remove the wire, then it's a "run solenoid", you will need to remove the solenoid (tape over the hole) to run the tractor and test it.
If you remove the wire and it stays running then it's a "stop solenoid", run it with the wire off and see how it does.

Report back with what you find.

 

[bear15]

Reading back through your symptoms I would be looking at stop solenoid and or wiring.
Real simple, remove the wire that goes to the stop solenoid while the engine is running.
If it stops running when you remove the wire, then it's a "run solenoid", you will need to remove the solenoid (tape over the hole) to run the tractor and test it.
If you remove the wire and it stays running then it's a "stop solenoid", run it with the wire off and see how it does.

Report back with what you find.

Test completed.

I removed the wire and it stayed running ("then it's a "stop solenoid", run it with the wire off and see how it does").

After about 10 min. it did the same thing and lost power. Then I put the wire back on to start it and it ran just fine for 10 min or so. Then I pulled the wire off and it ran just fine for another 10 min. or so and then lost power again. I put the wire back on and it ran just fine for 10 min or so. It repeated this pattern for awhile, but then began to run just fine with the wire on.

So what do you think the problem is?

Thanks for any help.

Ed

 

[North Idaho Wolfman]

Test completed.

I removed the wire and it stayed running ("then it's a "stop solenoid", run it with the wire off and see how it does").

After about 10 min. it did the same thing and lost power. Then I put the wire back on to start it and it ran just fine for 10 min or so. Then I pulled the wire off and it ran just fine for another 10 min. or so and then lost power again. I put the wire back on and it ran just fine for 10 min or so. It repeated this pattern for awhile, but then began to run just fine with the wire on.

So what do you think the problem is?

Thanks for any help.

Ed

Your problem is in fuel delivery and not electrical.
Might be the lift pump or some other part of fuel delivery.
Your next test would be to rig up a fuel container to gravity feed the injection pump, this will bypass anything else causing the issue.

Did you remove the fuel tank to clean it?

 

[bear15]

Your problem is in fuel delivery and not electrical.
Might be the lift pump or some other part of fuel delivery.
Your next test would be to rig up a fuel container to gravity feed the injection pump, this will bypass anything else causing the issue.

Did you remove the fuel tank to clean it?

See first post . . .
We have a Kubota B3030 diesel and it loses power, sometimes quits (continues going if I take foot off accelerator), but restarts just fine. It will go long stretches of time working just fine as normal, but then the problem occurs randomly. We have completed the following. Any suggestion appreciated.
-drained and cleaned fuel tank and fuel lines
-replaced fuel filter & fuel filter cup
-treated fresh fuel, good quality (works on our other diesel engines just fine), added fuel treatment
-replaced air filter

 

[North Idaho Wolfman]

See first post . . .
We have a Kubota B3030 diesel and it loses power, sometimes quits (continues going if I take foot off accelerator), but restarts just fine. It will go long stretches of time working just fine as normal, but then the problem occurs randomly. We have completed the following. Any suggestion appreciated.
-drained and cleaned fuel tank and fuel lines
-replaced fuel filter & fuel filter cup
-treated fresh fuel, good quality (works on our other diesel engines just fine), added fuel treatment
-replaced air filter

Yes I'm fully aware of what you said you have done.
You still did not answer my question, did you remove the fuel tank to clean it?

This is a simple diesel engine
It requires fuel and compression to run and that's it.
If it's not getting fuel it won't run, and that is what's happening.
Why it's not getting fuel is what you need to find out.

Bottle feed the injection pump, then if you still have a problem then you have either a failing injector (not very likely), a damaged injection pump (not very likely) or a failing governor (again not very likely)!
The most common failure would be the lift pump fuel lines, fuel tank, fuel filter housing.
I have seen more clogs in fuel filter housings than you would think, debris gets stuck in the inlet of the housing.
Also seen a lot of fuel tanks with mysterious debris in the bottom of the tanks that slosh around and randomly get stuck on the output, engine dies and the suction stops and the debris floats away then it runs again, until it gets sucked up again.

 

[old and tired]

Could a blocked Vent Cap cause any of this? Just remove the cap to check, easy enough to check.

 

[bear15]

Yes I'm fully aware of what you said you have done.
You still did not answer my question, did you remove the fuel tank to clean it?

This is a simple diesel engine
It requires fuel and compression to run and that's it.
If it's not getting fuel it won't run, and that is what's happening.
Why it's not getting fuel is what you need to find out.

Bottle feed the injection pump, then if you still have a problem then you have either a failing injector (not very likely), a damaged injection pump (not very likely) or a failing governor (again not very likely)!
The most common failure would be the lift pump fuel lines, fuel tank, fuel filter housing.
I have seen more clogs in fuel filter housings than you would think, debris gets stuck in the inlet of the housing.
Also seen a lot of fuel tanks with mysterious debris in the bottom of the tanks that slosh around and randomly get stuck on the output, engine dies and the suction stops and the debris floats away then it runs again, until it gets sucked up again.

Yes, totally took out the gas tank, bought and installed a brand new fuel filter and housing kit and everything is flowing just fine. How do I bottle feed the injection pump if the problem is random as described? e.g. it will run fine for 10 minutes or so without any problem at all. I'm sorry, this is a very strange situation to me and I certainly appreciate all your help.

 

[bear15]

Could a blocked Vent Cap cause any of this? Just remove the cap to check, easy enough to check.

Do you mean the vent on the gas cap or come other vent?

 

[North Idaho Wolfman]

Yes, totally took out the gas tank, bought and installed a brand new fuel filter and housing kit and everything is flowing just fine. How do I bottle feed the injection pump if the problem is random as described? e.g. it will run fine for 10 minutes or so without any problem at all. I'm sorry, this is a very strange situation to me and I certainly appreciate all your help.

Get a container ( like a bottle, or fuel can) attach it above the engine and run a hose to the injection pump directly.
That will eliminate the entire tractor fuel system.
Run it with the wire disconnected from the stop solenoid.
You will need to shut off the fuel or the lift pump will push fuel out.

 

[old and tired]

Do you mean the vent on the gas cap or come other vent?

Yup, plain "gas" cap!!!!

 

[bear15]

Yup, plain "gas" cap!!!!

Because I had to mow tall vegetation of 9 acres or so, and did not want to get anything in the gas tank (very dry weather), I checked the gas cap to make sure it was clean before I started and simply banged the top of the gas cap a few times when the engine started to hesitate. This seemed to work just fine.

So, I think I need a new gas cap?

 

[BAP]

Because I had to mow tall vegetation of 9 acres or so, and did not want to get anything in the gas tank (very dry weather), I checked the gas cap to make sure it was clean before I started and simply banged the top of the gas cap a few times when the engine started to hesitate. This seemed to work just fine.

So, I think I need a new gas cap?

You really need to stop referring to the fuel tank and cap as “Gas”. If you don’t then people including yourself think that you are putting gas in your tractor not diesel. You didn’t put gas in your tractor did you?