Kubota B7800 No Power At Fuel Stop Solenoid

[TomJ]

Tractor will crank but will not start. There is no power getting to the fuel stop solenoid so there is no fuel going to injectors. Fuses are good, seat and pto switches are good. Can't find any breaks or damage to wires. What am I missing in the circuit that can cause this problem?

 

[KennyV]

If it really is a fuel Stop solenoid It should Only have power supplied After the key is turned off, and then Only for about 5 seconds.
BTW ... If it has 2 wires it is a Stop solenoid and works like the above.
If it has 3 wires then it has a Pull winding and a Hold winding... Kubota has used both types on various tractors & engines. KennyV

 

[TomJ]

KennyV, The stop solenoid on my tractor works different.There are two wires running to the stop solenoid. When I run a hot wire to the stop solenoid the tractor will start, thus this set up needs power to the solenoid to open fuel flow for the tractor to start but that is not happening. So I go back to the same question, what is preventing power to the stop solenoid when the key is turned on. Again the fuses, seat and pto switches are all good. Does anyone know the purpose of the controller that is located behind the dash? Working on a 2008 Kubota B7800. TomJ

 

[skyhook]

On my L4200, there's a relay for this, it's also behind the dash.
Could be your problem "if" the fuse is good.

 

[KennyV]

On my L4200, there's a relay for this, it's also behind the dash.
Could be your problem "if" the fuse is good.

On the L4200, that relay behind the dash is a time delay... It will Apply 12 volts to the kill solenoid for around 5 seconds After you turn the key Off...
It sounds as if TomJ has a different set up.

 

[skyhook]

On the L4200, that relay behind the dash is a time delay... It will Apply 12 volts to the kill solenoid for around 5 seconds After you turn the key Off...
It sounds as if TomJ has a different set up.

Ok, thanks for that Ken. But he may have some sort of relay also.

 

[TomJ]

The tractor is now running again. The problem was a broken wire connection where it plugged into the fuel relay behind the dash console. It took a long time to hunt down because Kubota doesn't indicate a fuel relay in the wiring diagram of a B7800. Nor do they indicate one in their parts listing diagram. If you ever suspect that you might have a bad fuel relay that supplies power to the fuel shutoff solenoid to provide for fuel flow its parts number is ACA12115 (CA1a-12V-A-5). Two Kubota dealers I checked with had no listing on the fuel relay. You can find this relay on the internet by entering the part number.

 

[herringchoker]

Tom, glad you found it. Thanks for posting the solution. I will try to remember this if I ever run into that problem.

 

[Dan W]

Tom, glad you found it. Thanks for posting the solution. I will try to remember this if I ever run into that problem.

I agree, good work Tom, my B7800 is 2003 vintage so this knowledge will no doubt come in handy.

Dan

 

[Hai]

Tom, I am currentlt having exactly the same problem with my L3400 HST: no power to the fuel solenoid which has 2 wires. All fuses are good. All safety switches are fine. The engine cranks but would not start. My next attempt is checking the fuel solenoid relay, which is behind the dash. How did you find out about the broken wire connection, by visual or by multi-meter? Thanks.