issue with kubota starting.

[Heddenonin]

Hi all. I have a b2910. Had it for several years with little to no issues at all. Just a few weeks ago I started it and, within a few seconds, it died. I changed the fuel filter at that time and it seemed to resolve. I was able to run it until a couple days ago. At that time, I started it and within a few seconds, it died. Now, I can immediately restart it and then it dies again. It just keeps following that pattern. I've had to refuel a few times in the past couple weeks, so I'm not thinking there is old fuel in the tank. However, I have treated the fuel in the tank as well.
I've also checked the voltage supplied to the fuel stop solenoid. I'm getting a range of 10 - 11 volts. I did attempt to bypass the solenoid by connecting jumper wires to ground and the battery positive terminal. At that time, I heard the solenoid 'click'. But, when I plug the solenoid into the harness and turn the ignition key on, I don't hear the same 'click'.
I am a shade-tree mechanic. I don't know if I'm barking up the wrong tree with the solenoid. I've also thought about the safety interlock switches. However, if a switch were the culprit, the tractor shouldn't even turn over?

I would appreciate any assistance with this issue.
Tom

 

[Roadworthy]

You said you bypassed the solenoid but all you did was bypass the power. If the solenoid is failing it could still be turning off the fuel. You may have to replace it to see if it's failing or disconnect the output side to see if there's fuel flow when the engine dies.

 

[Dave_eng]

You need to have a better understanding of the engine stop solenoid.

There are two coils inside it. A PULL-IN coil and a HOLD coil.

The pull in coil is powered when the engine cranks. As soon as the key switch returns to the ON position from the START position the Pull in coil power is cut off.

At that point, if everything is working and all safety switches are satisfied, the hold coil takes over and holds the solenoid retracted so the engine can run.

The solenoid has two electrical terminals (one for each internal coil) and is grounded through the contact with the engine.

Check the obvious which would be a fuse.

Study the attached info.

Dave

 

[Palmettokat]

It is possible there is trash in the fuel tank. I had a wasp in my tank one time and it was about like that. Disconnect the line from the tank and see how it drains.

 

[whitetiger]

Hi all. I have a b2910. Had it for several years with little to no issues at all. Just a few weeks ago I started it and, within a few seconds, it died. I changed the fuel filter at that time and it seemed to resolve. I was able to run it until a couple days ago. At that time, I started it and within a few seconds, it died. Now, I can immediately restart it and then it dies again. It just keeps following that pattern. I've had to refuel a few times in the past couple weeks, so I'm not thinking there is old fuel in the tank. However, I have treated the fuel in the tank as well.
I've also checked the voltage supplied to the fuel stop solenoid. I'm getting a range of 10 - 11 volts. I did attempt to bypass the solenoid by connecting jumper wires to ground and the battery positive terminal. At that time, I heard the solenoid 'click'. But, when I plug the solenoid into the harness and turn the ignition key on, I don't hear the same 'click'.
I am a shade-tree mechanic. I don't know if I'm barking up the wrong tree with the solenoid. I've also thought about the safety interlock switches. However, if a switch were the culprit, the tractor shouldn't even turn over?

I would appreciate any assistance with this issue.


Tom

If you put Positive to one pin and Negative to the other pin at the connector, you will probably never hear it click again.

A simple test, remove the solenoid from the injection pump and start the tractor. Tractor stays running, you have an electrical problem. Tractor starts and dies, you have a fuel supply or mechanical problem.

With the solenoid off the injection pump, take a jumper cable from battery Negative to the metal body of the solenoid to ground it. Start the engine and watch the plunger pin sticking out of the solenoid. It should retract as soon as you start cranking the engine and should stay in until you shut the switch off.

 

[beex]

You need to have a better understanding of the engine stop solenoid.

There are two coils inside it. A PULL-IN coil and a HOLD coil.

The pull in coil is powered when the engine cranks. As soon as the key switch returns to the ON position from the START position the Pull in coil power is cut off.

At that point, if everything is working and all safety switches are satisfied, the hold coil takes over and holds the solenoid retracted so the engine can run.

The solenoid has two electrical terminals (one for each internal coil) and is grounded through the contact with the engine.

Check the obvious which would be a fuse.

Study the attached info.

Dave

I don’t think there is a hold coil, I think it’s just a spring snaps it back when the pull in coil releases.


Sent from my iPad using Tapatalk

 

[Dave_eng]

I don’t think there is a hold coil, I think it’s just a spring snaps it back when the pull in coil releases.


Sent from my iPad using Tapatalk

Look at the wiring diagram I posted.

Item #6, the cut off solenoid, the illustration clearly shows two coils inside the solenoid.

Further, there are two wires connected to the solenoid, one for each internal coil, and its ground is through the body of the solenoid.

Dave

 

[beex]

Look at the wiring diagram I posted.

Item #6, the cut off solenoid, the illustration clearly shows two coils inside the solenoid.

Further, there are two wires connected to the solenoid, one for each internal coil, and its ground is through the body of the solenoid.

Dave

yes, i did, look, and it looks to me there are 3 connections, and 2 of them are connected to the ground circuit to the bottom, and the third wire on top is the only wire that energizes.

The bottom of the diagram where the glow plugs, starter, safety switches, starter relay all connect is the ground, 2 wires from the solenoid go directly there.


Sent from my iPad using Tapatalk

 

[beex]

Look at the wiring diagram I posted.

Item #6, the cut off solenoid, the illustration clearly shows two coils inside the solenoid.

Further, there are two wires connected to the solenoid, one for each internal coil, and its ground is through the body of the solenoid.

Dave

Ok re-read what you wrote, i miss interpreted what you said, about the switch positions, and what is going on. I thought you were saying that when you turn the key off the hold coil holds the solenoid in cut off position.

Yes the solenoid has 2 coils, but I think the solenoid diagram or the wiring diagram is incorrect because like i said 2 of the wires go to ground, one on the ground side of the starter. Some 2 coil solenoids have a built in switch to turn off the pull coil. It looks to me that is the case here, so when you switch to on, both coils energize, and pull coil switches off automatically when energized, because I don’t see any difference electrically between start position and on position on the switch as to regards to energizing coils.

Or maybe the diagram is misleading at the connection to the starter and that’s not a ground connection, which case it works as you said.

Sent from my iPad using Tapatalk

 

[whitetiger]

It works as Dave stated.

 

[Dave_eng]

Beex

Trying to help you understand the diagram I posted....

Look at the Glow plugs. Each has two electrical connections but in reality one of those connections is the engine cylinder head providing the ground path back to the battery negative terminal.

The portion of the wiring diagram attached to this post is clearer in respect to the FRAME EARTH. i.e. ground to engine or tractor frame.

You can see the two internal coils in the solenoid. There is no internal switch.

Solenoids with an internal switch also have two coils but are fed with one wire not two.

Dave

 

[beex]

ok, thanks

BTW, my BX works differently, maybe the newer B do to. On my bx, the unenergized solenoid lets the fuel flow. When you turn it off, there is a timer to activate the solenoid to cut off the fuel for about 10 sec to shut down. After the timer expires, the cutoff is open. I like this better because any failure mode, the tractor runs, and you just manually shut down like you did in the old days. I don’t know why they added fuel shutoff solenoids at all, didn’t see anything wrong with a manual shutoff like diesels are supposed to have.


Sent from my iPad using Tapatalk

 

[Dave_eng]

ok, thanks

BTW, my BX works differently, maybe the newer B do to. On my bx, the unenergized solenoid lets the fuel flow. When you turn it off, there is a timer to activate the solenoid to cut off the fuel for about 10 sec to shut down. After the timer expires, the cutoff is open. I like this better because any failure mode, the tractor runs, and you just manually shut down like you did in the old days. I don’t know why they added fuel shutoff solenoids at all, didn’t see anything wrong with a manual shutoff like diesels are supposed to have.


Sent from my iPad using Tapatalk

Current safety legislation mandates much more positive control over when the engine can start, run and when it must stop to avoid injury hence the engine stop solenoid rather than a pull cable.

Your BX will have a "big brother," called an operator presence controller (OPC) watching the many safety switches and deciding when the engine can start, when it must stop and when it can continue to run if the operator is not in the seat.

As Kubota owners we are fortunate the technical material to help owners diagnose and maintain their tractors is widely available. Other brand's technical material is extremely limited to non existent.

John Deere is involved in huge legal battles with owners over the owner's right to service their tractors. John Deere maintains the electronic systems and technical resource material are proprietary and not available to owners.

Dave

 

[lugbolt]

as stated, there are two coils. The "ground" is through the case, with contact to the block (self-grounding). If you put + on one terminal and - on the other, you've fried one of the coils in the solenoid. Replace it. What is a coil? It is an iron core with a bunch of teeny tiny insulated wire wrapped around it. It is designed to carry a certain amount of current. Short circuiting it via battery voltage usually cooks the teeny tiny wire (or at the least burns the insulation off) inside the coil as it is applying more amperage than it is designed to carry.

BX's and others don't have this design and should be completely left out of the conversation. Including them into the conversation is a source of confusion to the original poster and anyone else who might be reading.

A lot of times one coil dies and causes a no-start condition or a start and die condition depending on which coil has failed. Not common but it will throw you for a loop if you can't read a wiring diagram or figure out how the solenoid works. JD (Yanmar) used a ton of this style solenoid which is how I got introduced with them, I sold/serviced JD for 11 years, then Deere pulled some stupid stuff and we told them to take their junk and we'd focus on Kubota. Now Kubota's doing some of the same stuff. A lot of challenges for the smaller dealers.

 

[SidecarFlip]

Had to replace mine on my M9 cab last year. I got the dealer item, was I think about a hundred bucks but you can get them of Flea-Bay for about half that but in my opinion, the quality is always suspect.

 

[Heddenonin]

Thank you for the info. My next issue is that I am unable to get to the bolt in the back (on the engine block side of the fuel cutoff solenoid). Any thoughts on how to remove this bolt?

 

[Henro]

I also have a B2910 so this thread caught my attention. I have a question.

In the first schematic Dave posted, it shows the engine solenoid as having two coils, but the left hand coil has both ends connected to ground so it cannot be functioning. So essentially there is only one coil that matters.

In the second drawing Dave posted, the engine solenoid again has two coils, but they are connected in parallel, so effectively work as one coil would, being either energized or de-energized simultaneously.

Neither drawing shows the start and hold function possible.

I understand the concept of a start and hold coil, but cannot see that function represent in either of these drawings. Are these drawings intended to be representative and not actually applicable to the B2910?

What am I missing?

OK, I was able to answer the question myself:

I just noticed Dave posted a PDF of the first drawing he posted, of that page in the manual, and it shows the drawing is in error. The wire shown on the drawing that shorts out the left hand coil cannot be there, or current would never flow through the left hand coil as shown on that manual page.

The wire shown in the drawing cannot be there in the real world, if the circuit is to act as described. Drawing is obviously in error.

I figured since I typed the above I would leave it in case someone else has the same question.

 

[whitetiger]

Here are 2 diagrams from the WSM to clear your mind.

 

[Henro]

Here are 2 diagrams from the WSM to clear your mind.

Thank you for posting those diagrams. If you look closely, they both show one of the two coils shorted across by a wire.

This confirms the error I was referring to. If each side of a coil is connected to the same point, electrically it can not operate.

So the diagrams are obviously in error, if the explanation of operation is correct.

 

[whitetiger]

Thank you for posting those diagrams. If you look closely, they both show one of the two coils shorted across by a wire.

This confirms the error I was referring to. If each side of a coil is connected to the same point, electrically it can not operate.

So the diagrams are obviously in error, if the explanation of operation is correct.

The Positive wires are separated, the only common is the ground which is done through the base, there is no actual ground wire,
The HOLD circuit is energized from the key switch, the PULL circuit is powered from the starter solenoid being engaged.