Fuel shutoff activating prematurely, as key is released during startup

[Twister T60]

Hey guys, I have a z482e4b-atk-1. The starter wouldn’t crank, and I decided I had a bad starter. The motor was inside a housing that was difficult to remove, so I had to remove the alternator and oil filter to get the starter out. I wiggled and pulled at the tight wire harness, maybe I casued an issue there? With everything back together, it cranked Nietzsche, but wouldn’t start. I noticed that the fuel shutoff solenoid activated the moment I let go of the key, during startup. So it wouldn’t actually run unless I belt the solenoid from shutting off, and then it let go, and the motor stayed on. Any ideas?

It’s almost as if the solenoid sees the key in the off position, when it’s actually in “run” position. If I simply unplug the timer relay, it starts fine, but of course, it won’t shut off, so I need to reach in and manually activate the fuel shutoff lever, connected to the solenoid.

I checked anything that might send a shutdown signal, such as temperature sensor, oil pressure sensor. I swapped timer relay with another one and had the same issue. I know it’s getting power, and operating, I feel it fighting me when I start it and hold it. But it’s getting the shutdown signal in “run” instead of in “off” position at the key. Is that a bad ignition switch? Maybe I connected a wire to negative that was supposed to go to positive, ar the battery terminal? I don’t think I mixed up any wires at the ignition, but that was a logical place to look. I don’t see anything out of place there, and everything is tight. I didn’t take a picture of the battery terminals, so who knows? I checked for continuity on every wire that I could see, and every plug there was. I’m out of ideas.

 

[North Idaho Wolfman]

There are 2 hot's running to the timer, one constant one keyed, you need to check if the keyed is losing power after crank.

 

[Twister T60]

There are 2 hot's running to the timer, one constant one keyed, you need to check if the keyed is losing power after crank.

There are 2 hot's running to the timer, one constant one keyed, you need to check if the keyed is losing power after crank.

My brain is so fried, I’ve been at this for two days. It’s a 4 pin plug. There’s an orange wire coming in with an inline diode. It’s tied to a green wire. That’s 1 pin. Looking at the end of the plug, going clockwise, next is red. Then black. Then red.

 

[Twister T60]

My brain is so fried, I’ve been at this for two days. It’s a 4 pin plug. There’s an orange wire coming in with an inline diode. It’s tied to a green wire. That’s 1 pin. Looking at the end of the plug, going clockwise, next is red. Then black. Then red.

Another thought is I have this one terminal that was connected to the battery. I traced it to the flywheel sensor. Do you think that should be going to minus or plus? I think the sensor housing is grounded, because it’s like a threaded bolt, bolted to ground. So I assume it should be positive. But I had it connected to negative. Maybe that’s effecting it not starting? But I’m scared to connect it to positive. Don’t want to brick this unit

 

[North Idaho Wolfman]

What's the motor in or running?

 

[Twister T60]

What's the motor in or running?

It’s running an airworks twister t60 rotary air compressor. Btw, the first red wire mentioned has no voltage at on position, and no voltage during cranking the starter. But as soon as I let go of the key it gets 12v, which totally checks out. That’s what activates the solenoid and shuts off fuel. And the second red wire always has 12v, in the off position, run position, and while cranking.

What's the motor in or running?

airworks twister t60. And btw, first red wire mentioned shows no voltage at off, run, or cranking. But as soon as I release the key, it activates at 12v, and shuts the fuel off. Second red wire is constantly at 12v in every key position

 

[Twister T60]

Do you think the key positions are messing up in my ignition?

I guess If I unplug the connector at the solenoid and bypass it to a momentary switch, and back again, I can start it and still shut it off by pressing the momentary switch. But I wish I could figure out what I did wrong. Do you think a disconnected flywheel sensor could have anything to do with it? Would it be stupid for me to connect it to positive battery terminal? Do you know how those work?

 

[PoTreeBoy]

It’s running an airworks twister t60 rotary air compressor. Btw, the first red wire mentioned has no voltage at on position, and no voltage during cranking the starter. But as soon as I let go of the key it gets 12v, which totally checks out. That’s what activates the solenoid and shuts off fuel. And the second red wire always has 12v, in the off position, run position, and while cranking.

airworks twister t60. And btw, first red wire mentioned shows no voltage at off, run, or cranking. But as soon as I release the key, it activates at 12v, and shuts the fuel off. Second red wire is constantly at 12v in every key position

You may have a bad keyswitch. The black wire will be ground. As NIW said, one wire, red, will be hot always. Sounds like you have that. One wire, maybe red w/ black, should be hot when the key is in acc or start. The fourth wire goes to the stop solenoid. There may be two fuses involved also.

 

[North Idaho Wolfman]

Without the wiring diagram for your use I couldn't tell you what the flywheel sensor is doing or how it should be wired.
It shouldn't have anything to do with the shutdown solenoid but it might.
Tractor and normal kubota equipment doesn't use any flywheel sensors.

Can you get a wiring diagram for the unit?

 

[Twister T60]

Without the wiring diagram for your use I couldn't tell you what the flywheel sensor is doing or how it should be wired.
It shouldn't have anything to do with the shutdown solenoid but it might.
Tractor and normal kubota equipment doesn't use any flywheel sensors.

Can you get a wiring diagram for the unit?

yes, here it is. I’ve stared at this and checked continuity on everything. Everything seems right. All sensors on yellow rail show continuity. Red wires on relays check out with starter. Orange wire on relay checks out on alternator signalwire. Diode passes test, green wire spliced to orange at timer checks out too. I’m beginning to think it’s this $35 ignition that takes a week to get here and I can’t work without this compressor.

 

[Twister T60]

You may have a bad keyswitch. The black wire will be ground. As NIW said, one wire, red, will be hot always. Sounds like you have that. One wire, maybe red w/ black, should be hot when the key is in acc or start. The fourth wire goes to the stop solenoid. There may be two fuses involved also.

Yea the two 30 amp fuses were checked. The only other thing is this mystery wire that I’m pretty sure is supposed to be hooked to negative. Appears to feed magnetic flywheel sensor. Maybe it’s supposed to go to positive? Maybe there’s a fuel shutoff tied in somewhere if the flywheel isn’t turning? I’m a noob so I don’t know if that makes any sense or not. Should I risk hooking it to positive? Maybe that fixes everything.. I was thinking maybe run a 5 amp fuse online, so if it’s not supposed to be positive, it might prevent burning something out. Scared to do it. But I think that sensor just feeds into the “shocker pass” system which I’ve had unplugged since day one.

 

[PoTreeBoy]

Yea the two 30 amp fuses were checked. The only other thing is this mystery wire that I’m pretty sure is supposed to be hooked to negative. Appears to feed magnetic flywheel sensor. Maybe it’s supposed to go to positive? Maybe there’s a fuel shutoff tied in somewhere if the flywheel isn’t turning? I’m a noob so I don’t know if that makes any sense orTha not. Should I risk hooking it to positive? Maybe that fixes everything.. I was thinking maybe run a 5 amp fuse online, so if it’s not supposed to be positive, it might prevent burning something out. Scared to do it. But I think that sensor just feeds into the “shocker pass” system which I’ve had unplugged since day one.

Thanks for the schematic. Do you happen to have the control panel schematic? Your compressor has some shutdown features, oil pressure, engine temp, air compressor fault, that most Kubota tractors don't have. I don't see a flywheel sensor on here.

Solid state electronics is definitely not my strong suit. But that green wire should, I think, have 12v when the engine is running. The wire and diode from the starter solenoid wire are to pull in until the engine is running. It's not clear to me what keeps that 'hot' if the oil pressure switch hasn't opened when the starter deenergizes. It's also unclear to me how a normal shutdown occurs without the control panel schematic.

Maybe @GreensvilleJay can shed some wisdom here.

 

[Twister T60]

Thanks for the schematic. Do you happen to have the control panel schematic? Your compressor has some shutdown features, oil pressure, engine temp, air compressor fault, that most Kubota tractors don't have. I don't see a flywheel sensor on here.

Solid state electronics is definitely not my strong suit. But that green wire should, I think, have 12v when the engine is running. The wire and diode from the starter solenoid wire are to pull in until the engine is running. It's not clear to me what keeps that 'hot' if the oil pressure switch hasn't opened when the starter deenergizes. It's also unclear to me how a normal shutdown occurs without the control panel schematic.

Maybe @GreensvilleJay can shed some wisdom here.

I don’t have any more schematics. The ignition is this:https://www.amazon.ca/gp/aw/d/B0DNJNMS6N?ref=ppx_pt2_mob_b_prod_image

It’s a1e01363590. By the way, that flywheel sensor is probably totally separate, added by the safety team, because some of these go to the mines, they need to make sure they can be shut off by air intake.

regarding the oil pressure sensor, you’re saying if the sensor doesn’t detect oil pressure it will activate the fuel shutoff? Won’t it take a few seconds to get oil pressure though? I’ll take a close look at the green wire again. Thanks.

 

[Twister T60]

I figured it out. Thanks everyone! That green wire led me to a transistor, taped up inside a loom between the main relay and the timer relay!

 

[PoTreeBoy]

I don’t have any more schematics. The ignition is this:https://www.amazon.ca/gp/aw/d/B0DNJNMS6N?ref=ppx_pt2_mob_b_prod_image

It’s a1e01363590. By the way, that flywheel sensor is probably totally separate, added by the safety team, because some of these go to the mines, they need to make sure they can be shut off by air intake.

regarding the oil pressure sensor, you’re saying if the sensor doesn’t detect oil pressure it will activate the fuel shutoff? Won’t it take a few seconds to get oil pressure though? I’ll take a close look at the green wire again. Thanks.

OK, so that may be an overspeed detector to trip the air damper. Probably also cut the fuel.

Caveat: my limited experience. I once dealt with an engine powered air conditioner. Once you flipped the ignition switch, you had x seconds to get the engine started and oil pressure up or it shut down. I don't see anything on that schematic that would provide that time delay, but it could be built into that style shutdown timer, or some other way.

My L35 has the shutdown timer, but it has no safety shutdowns. A wire from the ACC on the keyswitch provides 12v which resets the timer. When that 12v shuts off, it causes the contacts to close (actually this may be done with solid state, but it has the same effect) and starts the timer. When the timer times out, 10 sec or so, it opens the contacts.

Your machine, with the safeties, I think, provides 12v signal through a transister. When any of the safety switches goes to ground, the transister turns off (or on) to remove the signal and trigger the timer.

 

[PoTreeBoy]

So you got it going? Was the transister bad?

I forgot to mention that little box on the yellow wire from the transister is an unknown, but I guess it doesn't matter now.

 

[Russell King]

So you got it going? Was the transister bad?

I forgot to mention that little box on the yellow wire from the transister is an unknown, but I guess it doesn't matter now.

If you look closely at the picture of the transistor, it looks like two wires were NOT connected to the transistor any longer (green and yellow). But that is assuming they were supposed to be connected!

Hopefully @Twister T60 will post more details on what was wrong.