Kubota B7800 No Power At Fuel Stop Solenoid

[BookWood]

It's Memorial Day, 2022, tractor is dead in the vineyard.
What I learned:
1) Both seat sensors are working (Side lesson; seat tip-up sensor is so you can operate rear PTO WITHOUT your butt in the seat and tipping it back will shut off the unit),
2) Typical fuel solenoid is 2 wire, 12v HOT to remain open and supply fuel.
2a) "It should Only have power supplied After the key is turned off, and then Only for about 5 seconds.
It may have 3 wires "then it has a Pull winding and a Hold winding...
Kubota has used both types on various tractors & engines." KennyV
3) Relay under the dash; (TomJ, "...fuel relay... ACA12115 (CA1a-12V-A-5)" via internet. TomJ

I'm going out to feed the mosquitos, jump the fuel solenoid to try and get this back to the shed. I hope to do this without tearing the dashboard apart. I can't access the center, rear PTO safety switches or the Fwd/Bwd pedal safety switches safely on the soft earth of the vineyard.

to be continued...

 

[LouNY]

If you can reach it and access it disconnect the fuel solenoid and manually operate it.

 

[Henro]

This may help. From the B7800 supplement to the B2910 WSM.

 

[Henro]

You can download the WSM at kubotabooks.com for free:

http://kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=B2410_%20B2710_%20B2910_%20B7800_9Y011-13031%5B1%5D%20WSM.pdf

 

[Ed ke6bnl]

This may help. From the B7800 supplement to the B2910 WSM.


View attachment 748217

I do not understant the Controllers function delay timer to hold fuel cut signal from controller to fuel cut solenoid for 1 second.?? unless that is for the off the seat fast to run stationay pto equipment.

 

[LouNY]

On that model the fuel solenoid is activated to stop the engine,
after the time delay it de-energizes and lets the fuel stop return to the run position.

 

[BookWood]

Thank you LouNY (so no one pronounces "LOONY" do they? ), thank you also Henro & Ed. I don't understand the relay logic either.
I hot-wired the normally closed fuel solenoid, took a butterknife to the battery hot + solenoid, key on, and it started up.
There was, however a click-click-click-clicking from the fuel stop (or somewhere around there) the whole time at about 1Hz or less and it was running rough. (??)

Made it to the shed, removed the belly mower, raised it up a bit with the bucket, chocked the wheels and set the frame on jack stands.

Thanks again Henro for the documentation. I figg'rd there were six interlock switches. Have yet to locate the clutch switch but know
its there somewhere having had nothing happen on occasion when turning the key with no results, wondering where my left foot was.

I'm going check the open or closed requirements for each switch and jump closed or leave open as required (multimeter), and turn the key.

If that don't go I'll remove the steering wheel and dashboard and look for rats and broken wires and test the ignition switch function again.

Open side of the shed is in full sun, temp was about 85 (in the shade) and just now the sun is going behind the trees. I'll hit this again in a little bit.

 

[LouNY]

Thank you LouNY (so no one pronounces "LOONY" do they? ), thank you also Henro & Ed. I don't understand the relay logic either.
I hot-wired the normally closed fuel solenoid, took a butterknife to the battery hot + solenoid, key on, and it started up.
There was, however a click-click-click-clicking from the fuel stop (or somewhere around there) the whole time at about 1Hz or less and it was running rough. (??)

Made it to the shed, removed the belly mower, raised it up a bit with the bucket, chocked the wheels and set the frame on jack stands.

Thanks again Henro for the documentation. I figg'rd there were six interlock switches. Have yet to locate the clutch switch but know
its there somewhere having had nothing happen on occasion when turning the key with no results, wondering where my left foot was.

I'm going check the open or closed requirements for each switch and jump closed or leave open as required (multimeter), and turn the key.

If that don't go I'll remove the steering wheel and dashboard and look for rats and broken wires and test the ignition switch function again.

Open side of the shed is in full sun, temp was about 85 (in the shade) and just now the sun is going behind the trees. I'll hit this again in a little bit.

Has happened more then once, I try and take it in context, and as long as I get called for meal time all is good

 

[BeezFun]

I do not understant the Controllers function delay timer to hold fuel cut signal from controller to fuel cut solenoid for 1 second.?? unless that is for the off the seat fast to run stationay pto equipment.

I think it's to prevent nuisance power losses from things like bouncing up and down in seat. My wife is so small that she barely trips the seat safety switch and when she bounces up and down in the seat on our lawn tractor the engine is constantly losing power briefly as she bounces across the yard driving way too fast.
In the schematic above, switch #12 (the seat reverse switch) is what allows the rear PTO to run while the seat is folded forward.