Kubota B21 Fuel Stop Solenoid Issue

[RobbieBones]

Ok found the relay starter. Denso 056700-6690 or new part number 35800-75070. The plug has 2 reds a black a white/blue.Testing the plug to relay I get 12v with ignition off to a black and one red nothing else. Ignition on same thing only 12v to one red. Shouldn't both reds go hot?

 

[100 td]

Ok, let's clarify a couple of things as what you say leads me to think someone has done a big wiring change, which makes it difficult to diagnose, or you are unsure as to what has been done to the wiring.
First you say

It's a 2007 B21 with OPC (which is Bypassed at this time)

So the OPC controller is no longer in circuit and the wiring around this controller has been manually bypassed. Therefore, the control for the starter motor no longer comes from the OPC, but would need to come from the key switch or a relay controlled directly from the key switch and the control for the fuel stop solenoid relay no longer comes from the controller, and would need to also come directly from the key switch?

Later you say

I have the seat safety switch bypassed and was standing alongside the tractor. It just stopped running.

If you have the OPC bypassed, the seat switch plays no part in the circuit.

Do you have the OPC bypassed, or do you just have the seat switch bypassed?

Ok found the relay starter. Denso 056700-6690 or new part number 35800-75070. The plug has 2 reds a black a white/blue.

The wiring of the KEY STOP SOLENOID RELAY in a B21 with OPC has 2 x heavier Red/Blacks, 1 x medium Black, and 1 x small White/Blue wires going to it. There is no starter relay in the B21 with OPC, the starter is controlled by the OPC.
The Blue/white is the control circuit coming from the OPC.

I did find two wires coming from the square black box under dash were chewed by mice. I wrapped them each in electrical tape.

You mean from the BYPASSED OPC? So are these wires chewed through, or is it just the insulation that is chewed. I expect you may need to go back and have a decent look at those wires. What color are the wires?

Getting back to the FUEL STOP SOLENOID - as I mentioned previously, it "appears" your solenoid may have a SWITCHED pull in coil for protection of the pull in coil.
To test and PROVE the operation of your solenoid correctly, you need to power the "hold in" coil, then also power the "pull in" coil, then remove power from the "pull in" coil.
The hold in coil won't pull the solenoid in, but will draw a little power and may move the plunger a smidgen. This is like when the key is in the ON position. When you then also power the "pull in" coil, the coil will pull in and stay in, even when you disconnect power from the pull in coil. So normally for this style of coil, you turn IGN on, hold in coil is energized, then turn to START, and pull in coil is energized which pulls the solenoid in, you release the START key back to IGN, the hold in coil continues to HOLD the solenoid in.

The above is testing for a normal style 2 circuit solenoid coil. From the wiring diagram I have it shows both circuits being energized together, that's why I believe it has a switched pull in coil, and you're testing saying it goes off like a machine gun confirms that style, because when the coil pulls in, it disconnects/switches the pull in coil off so it doesn't burn out, and then if the hold in coil is not energized, it will pop back out and re-energize and come back in. Test the solenoid as above and see what you get.

I expect the OPC is actually still in circuit and is probably functioning correctly, I expect your solenoid is OK, and you have some chewed wiring to deal with, and if it's chewed in one place, it may be chewed elsewhere. The chewed wiring is probably affecting inputs or outputs to or from the OPC and the correct operation of the OPC. However, the OPC could be faulty, or you are missing other critical inputs such as PTO and HST inputs etc.

 

[RobbieBones]

100td Thank you for your help. Wish I was more of a mechanic or electrician so I could explain things better.

First the OPC, I thought that meant just the safety switch for the seat. My mistake, the safety switch I bypassed was at the seat switch with a jumper wire. All other safety switches are working. Meaning clutch needs to be down, forward and reverse needs to be centered etc to start the machine.

I understand know that the black 2x3 box under the dash is the OPC unit. (Coleman parts calls it a Controller) That is still hooked up and I found two wires with the installation chewed off which I repaired. The tractor started a few time as it normally should after that repair. Then while I was off the tractor with it running it just died. A day earlier before this repair the tractor gave me a hard time starting, I realized it was the solenoid because I wasn't getting any smoke out the exhaust while turning the key. I didn't hear the usual click either. Then for no reason I turned the key heard the click and the machine started. Ran it half a day. Shut it off and again it happened. That is when I removed the solenoid, the dash, and found the wires. Wrapped the wires, tested the solenoid with a jump from the battery and it sounded like a machine gun.

After read some responses I tested the solenoid with two hot wires and grounding it to the engine and the solenoid locked in and stayed in.

The wiring for the key stop solenoid relay is excactly like you describe. (Coleman Parts calls it a starter relay) I used the wrong terms to describe the part. There is an OPC it is connected.

In the morning I'll double check all the other inputs and test the fuel stop solenoid.

If the wires on the OPC all check out and the other inputs are good. Then it is the key stop solenoid relay that is bad? Why is only one red/black to black hot? What makes the other red/black hot from the key stop solenoid relay? When I removed the key stop solenoid relay) the small black unit bolted to a brass colored bracket near the OPC) there is a rattling noise, is this normal?

 

[RobbieBones]

100td anyway you can post the wiring schematics? Thanks for your time.

 

[100 td]

Can't post diagram at the moment, my HDD crashed/wouldn't boot yesterday and I am in process of try to save everything I can, scanner is off network at the moment (I shouldn't be wasting my time on here!) Will try tomorrow, see how I go. When the relay is energized the other red/black will become hot when the relay closes and switches it to the existing hot red black.
For the fuel relay to turn on, the blue/white needs to be energized by the OPC.
The OPC needs HST, PTO and seat switch, and start signal from key switch.
The clutch pedal switch is directly in circuit with the starter motor solenoid which is controlled from the OPC.
As mentioned previously, your OPC could be bad, but you need to ensure everything else is correct. Not sure about the rattle, but for it to work it needs power on blue/white as noted above. When it gets that, the 2 x red/blacks are joined at the relay powering the wire going to the solenoid. At some point both solenoid wires are joined together in the harness or at a connector (per the diagram). This is why I said the solenoid must have a switched pull in coil, otherwise it would burn out.

I don't know the exact logic of the OPC controller but I'd hazard a guess that it won't cut the fuel for say 500msecs when the seat is in the forward position due to you bouncing on the seat on a bumpy road.

 

[RobbieBones]

Update.

Fuel stop solenoid tested good. I was able get it to hold in with only power to one wire.

The wires that were chewed on the OPC were Blk/WH, BRN/RD, WhT/BLK.

I was able to get power to the key stop solenoid wh/blue. But only after monkeying around with the OPC unit.

It appears the OPC unit has a fault in it. After putting the fuel stop solenoid back on and everything in place I was able to get the tractor to start. However moving and or squeezing the OPC unit the tractor would shut down.

I think bad OPC!

 

[RobbieBones]

100td thank you for all your time. Hope you get your PC up and running.

 

[CalG]

A little off topic, but this fuel cut off issue has been discussed several times over the past months.

I have looked on line using the google search, but have not seen a "generic" fuel controller offered.
I have a Mitsubishi engined tractor with a Mitsubishi fuel control module that has symptoms much like the OP. (two wire solenoid, random cut out, and random no start.)
I've just disconnected the solenoid and use the manual fuel cut off lever to stop the engine I really should repair the control by the key switch.

 

[RobbieBones]

CalG,
It was more of a safety issue with my machine. To turn it off without a fuel stop solenoid I had to use my finger or screwdriver. In the end it ended up being even more of a safety/headache issue because it turned out to being my OPC unit that controls even more then just the fuel stop solenoid. My machine would just die on me. Looks like $114 fix for me.

A little off topic, but this fuel cut off issue has been discussed several times over the past months.

I have looked on line using the google search, but have not seen a "generic" fuel controller offered.
I have a Mitsubishi engined tractor with a Mitsubishi fuel control module that has symptoms much like the OP. (two wire solenoid, random cut out, and random no start.)
I've just disconnected the solenoid and use the manual fuel cut off lever to stop the engine I really should repair the control by the key switch.

 

[100 td]

Couple of extra pages on the OPC as well, I hadn't looked at them, only the main diagram. Ha, upside down and all, you'll have to flip them. Check you wiring and connections thoroughly and see if you can get it all working back to original spec. Pull the OPC and check the pins/connectors, and perhaps if it's easy, check solder/wire connection on the PCB if there is one. Not sure will attach here very well, will give it a go, if it doesn't work, message me your email.