BX23 Stop Solenoid Function

[RStricker]

I recently purchased a 2005 Kubota BX23. It's not received the best of care, and the electrical system has had lots of "field modifications". It appears that essentially all safety switches have been cut out of the loop.

When I first started using the tractor, it would intermittently stop. No rhyme or reason to the stopping, just randomly stop. It would almost always start up immediately, but I never knew when it would stop. I replaced the fuel filters and made sure the booster fuel pump was adequately tied in to the 12v power. Also, turning the key off would sometimes stop the engine, and sometimes not - this is why the previous owner had connected a link to the fuel shutoff lever on the side of the injector pump!

In my efforts at troubleshooting, I started trying to figure out the stop solenoid. My multi-meter said that at all times there was no power going to it. So i disconnected it electrically (I just unplugged the connector wires) - and all of a sudden my problem went away. The engine continues to run until I reach down and pull the link to the fuel shutoff lever!

I'd like to restore the tractor electrical functions to something close to the original factory design, but I really need to understand the function of the stop solenoid. I bought the factory service manual, but the couple of paragraphs related to the stop solenoid are not correct. The manual shows a 3-wire connection in the discussion of stop solenoid troubleshooting, whereas the electrical schematic, and my machine have only 2 wires. If the stop solenoid has no power going to it while the tractor is running, and certainly will have no power going to it while the key is off - then how on earth does this thing work?

This is enough to make my head hurt - I'd appreciate a clear and simple explanation of what's supposed to be happening here.

Thanks for your input!

Robert Stricker

 

[KennyV]

Kubota, and many others have had 3 different types of fuel solenoid systems...
With that in mind, do remember that originally there was only a mechanical pull lever on Most diesel systems to stop the engine...
The most common electrical systems used to manage fuel shut off include:
(a)...3 wire systems, where the solenoid actually has 2 winding's, one PULLS the solenoid to turn the fuel ON, Then automatically switches over to the HOLD winding that holds the fuel on, when you cut power it releases and the fuel shuts off.
(b)...2 wire systems have a single winding and it Holds the fuel ON while power is applied, releases when the key is turned off.
(c)...And the third system is also a 2 wire solenoid BUT it is a Kill solenoid, with that system the fuel is Always on at the injector pump, but when you turn the key off there is a timer relay that will pulse the Kill solenoid for 5 seconds or so, Holding the fuel OFF for enough time to allow the engine to stop... then the timer relay deactivates, and the fuel is turned back on, ready for the next time the engine is cranked over..... KennyV

 

[RStricker]

Thanks KennyV,
A further review of the electrical schematic shows that this system has a timer relay ahead of the solenoid, making this the 3rd system that you describe above. I appreciate the explanation.