Kubota B21 Fuel Stop Solenoid Issue

RobbieBones · Apr 21, 2017

I had an issue starting the machine, realizing I had this issue in the past I knew to look at the stop solenoid. Played around with it and for some reason the tractor started again. Ran it half a day then while using it with the front bucket up it just died! I could not get it to start.

I have had this issue in the past and replaced the stop solenoid to solve my problem. I believe that was the last time I was on this site. Anyway the problem is back. Its a two wire solenoid when I pull it off the engine I can start the tractor no problem, runs fine. When I test the solenoid with a jump from positive terminal and grounding it, it sounds like a machine gun going in and out repeatedly never locking in or out. Ohms test shows 0 all around. So I believe its bad. My other problem is I do not have voltage to the two wire lead at all no matter what the position of the key is. I had voltage once while messing around with the solenoid but now no matter what I do I can't get voltage to the plug, (even cut the wires to check if it was the plug) no voltage. Fuses are all good and cleaned.

So I also pulled the ignition switch, it has 4 wires, using the red wire on the plug and a jumper wire I get power to dash, then glow plug but I can't jump start the engine. Not sure if I'm suppose to be able to ??? I Put the key in and turn it, engine starts. I was doing this trying to get voltage to the fuel stop solenoid with no luck.

So what provides the voltage to the fuel stop solenoid??? I think in the run position there should be voltage to the solenoid. At what point in the turn of the key should I've heard the click of the solenoid or get voltage to the plug? Is there a way to check the ignition switch properly? Is There something else to check? Thanks in advance for the help.

David_Kb7uns · Apr 21, 2017

A keystop solenoid only has power for 5-10 seconds after key is turned off or one of the safety switches is tripped. No power in run position and power is usually supplied to the solenoid by the keystop timer relay. Solenoid should pull in solid and vibrate.

David

RobbieBones · Apr 21, 2017

I'm not getting voltage at all to the solenoid. Does that mean a relay is bad or the ignition? I believe when it worked I would turn the key and hear a distinct click, continue turning key the tractor would start. I guess the click was the solenoid retracting, pulling out of pump, enabling fuel to injectors? It is then held out with voltage? Or is it suppose to stay locked in/retracted when off or tractor is running with no power to solenoid?David[/QUOTE]

QUOTE=David_Kb7uns;4746133]A keystop solenoid only has power for 5-10 seconds after key is turned off or one of the safety switches is tripped. No power in run position and power is usually supplied to the solenoid by the keystop timer relay. Solenoid should pull in solid and vibrate.

KennyV · Apr 21, 2017

Kubota has used 2 types of fuel control solenoids, you will have 1 OR the other:
1. Fuel shut off (Has 2 wires) and uses a shut off timer to supply power for about 10 seconds After key is turned off.

2. Fuel Turn on and hold on Solenoid (has 3 wires) Gets "pull On power" during engine crank, Gets "hold On power" when key is in run position.
You say you have 2 wires so it should be the 1st type... all it ever does is kill fuel flow... (gets 12 volts for about 10 seconds) from a timer relay, AFTER key is turned OFF.
One of your wires is Ground the other is the timed 12 volts...

100 td · Apr 22, 2017

My B21 FUEL STOP solenoid has a 3 wire solenoid, from my info should get power on white when key on, and red when cranking, ground is black. White to black is ~15 ohms, red to black 0.4 ohms. If you have a late model with OPC (operator presence control) from my diagram you could have a 2 wire solenoid with metal case to ground, and from the wiring it shows both wires are energised together, probably only for shutdown, but there are many faults in kubota diagrams so I couldn't be sure.

100 td · Apr 22, 2017

Is this an original solenoid? Part number from tag? Try powering both wires at the same time, while grounding the case and see what happens. It's possible that it has a switched pull in coil to protect it.

RobbieBones · Apr 22, 2017

Thanks for the responses. It's a 2007 B21 with OPC (which is Bypassed at this time). It has two red wires to the solenoid red,red/black never tried power to both but i believe it grounds by the unit being bolted to engine at least thats the only time it reacts when I put power from battery to it. Where and what does the timer look like? Anyway of checking the ignition?

RobbieBones · Apr 22, 2017

When I put test voltage from battery to both posts on solenoid it retracts and stays retracted. Disconnect one post and rod goes out. So I'm not getting voltage in the 2 red wires.

KennyV are you sure (2wire) does not stay energized while the tractor is running???

David_Kb7uns · Apr 22, 2017

Near as I can tell from looking at B21 pictures on the internet you have the dual circuit (coil) solenoid (it bolts to end of injection pump) and it is using the tractor ground instead of a third wire.

David

RobbieBones · Apr 22, 2017

David thats what I have. When I put voltage to both prongs on solenoid and have the unit touching the engine the unit retracts and stays there take power away and the rod comes out. What I'm trying to figure out is why I can't get power to the two wires that go to the solenoid. I'm thinking its the starter relay which is under the dash. Nothing I touch or clean gets power to the solenoid. The last time the machine was running with solenoid in the machine just stopped running on its own. I have the seat safety switch bypassed and was standing alongside the tractor. It just stopped running.

I did find two wires coming from the square black box under dash were chewed by mice. I wrapped them each in electrical tape. Maybe they shorted something out. But I did that before the tractor started normally and then just died.