Need Help Troubleshooting Fuel Shut-off System on BX24

[bkdamkr]

Can anyone help me troubleshoot the fuel shut-off system on my BX24? I've seen so many different descriptions of how the system works, I'm not sure what to check, where, and under what conditions.

My problem, which seems to be pretty common, is that turning off the key on my BX24 doesn't turn off the tractor. I can turn it off by pushing in the rod of the fuel shut-off solenoid.

How does the system work? Here is my best guess. While the engine is running, there is no voltage across the input of the solenoid. Turning off the key puts 12V across the solenoid input, moves it, stops the fuel, then removes the 12V after some period of time, maybe 5 seconds. Is this correct?

One obvious problem I have is that the wire running from the loom into the solenoid boot isn't connected to anything inside. I suspect that it is to be attached to the "tab" protruding from the end of the solenoid housing. Is this correct?

When the key is in the "on" position, there is no voltage between the wire and ground. Turning the key off does not appear to put 12V between the wire and ground. This suggests that something is amiss upstream, perhaps a bad ignition switch, fuse, or connection? Is this correct?

I connected a 12V battery to the tractor's ground using a small jumper wire. I then touched a jumper wire connected to the battery "+" terminal to the "tab" protruding from the solenoid housing. There were sparks and the jumper wire started to warm up rapidly, but the solenoid didn't move.

The approach I'd take going forward from here would be to work upstream from the wire that should connect to the solenoid and see if I can find that 12V "pulse" anywhere. Is this a reasonable approach?

If I'm on track, where, physically, should I be checking the voltage? Is there a better way to troubleshoot this system/

Thanks,
Brian

 

[David_Kb7uns]

There are 2 circuits. The solenoid is keystop, energized to pull plunger and move stop lever to kill engine. There is a keystop timer relay that energizes for the specified time and then turns off. The keystop timer relay is connected to the seat, pto and key switch circuits and turns on when the power to the circuit turns off.

Check fuses (2 circuits), check interlock switches and wiring make sure solenoid works and the timer relay is working properly.

David

 

[Tractor Seabee]

My BX 25 is the next generation up from yours, maybe the wiring diagram from the WSM is the same. By Monday I will be back where my WSM is and take a look at the diagram. Hope you figure it out the hard way before then. From previous perusals of the WSM there are a lot of interlocks to that circuit.

Ron

 

[bkdamkr]

Thanks. It's been pouring here and I haven't been able to get to it yet. David, where is the timer relay? And forgive me from being dense, but what does "keystop" mean in this context?
Thanks again,
Brian

 

[David_Kb7uns]

Think timer relay is under dash up on firewall.

Keystop refers to, method of stopping the engine. On the older diesel tractors you would have a keys witch for activating glow plugs and starter but there is a lever or knob for stopping the engine.

Engine shutdown is now done by energizing the solenoid by the activation of the timer relay that energizes when power to the relay is interrupted by either turning off key switch or breaking the circuit in the interlocking switches on the seat and PTO .

David

 

[Tractor Seabee]

Brian, here is the diagrams and info from the BX 25 WSM as promised. Hope there are no major differences between the 24 and 35. Wiring Diagram is 11 X 17, the other two are 8.4 X 11.

Ron