Lastec 3372 Kubota Engine Will Not Fire

[Stubbyie]

Sounds like you've checked everything thus far that I would have. Getting short on ideas, working at a distance.

Sill suggest you locate wiring diagram.

Your description makes me think the 12-v sent to stop solenoid travels through it then to the starter solenoid and allows it to engage---a sequential flow of power from one device to the next designed to shut down if any one component fails. But this is just a guess at this point.

I'm now back to the 9-v you saw during 'crank' condition. Wondering if weak battery (also possibly bad chassis ground) just won't fully engage the stop solenoid and/or spin the starter enough to roll it over and fire the engine.

Also refer to your bench test. If your description is that the stop solenoid cylces in-out-in-out-in-out repeatedly while hooked up then it is bad. It should retract (or push, whichever) and hold on application of power, then release when disconnected.

My guess however is that if the stop solenoid holds one position when powered then releases when disconnected, then it would be good. Possibly back to weak battery.

Then you're back to tracing other problems. What about safety switches, perhaps a PTO or gear shift or seat switch or clutch or something similar?

Have you thought about proving a start by bypassing all the extras and jumping from battery directly to starter? CAUTION make certain out of gear.

Continue keeping us informed. Maybe an idea will pop up on the forum.

 

[gene]

Stubbyie,
Thanks for the input. I'm trickle charging the battery and even though it cranked the engine reasonably well, it jumped to 8 amps on the charger when I first plugged it in; so may have been weaker than I thought. Related to the chassis ground; yesterday I completely cleaned and wire brushed the ground site such that it should not be an issue at this point.

Concerning the stop solenoid bench test: The prong cycled in and out very fast, maybe 10 times or so per second. The prong on the solenoid is extended when it is not energized and I have noticed the same default position on solenoids in parts catalogs that I've seen. Based on what you say, it should retract and stay in that position when energized and release when disconnected. So............. it seems like a bad stop solenoid.
Sounds like I need to price them at this point.
Gene

 

[Apogee]

You might try applying power across the two terminals rather than between the case (ground) and only one wire. The pulsing you're experiencing might be caused by an intermittent ground.

I'd also check resistance between the two terminals.

You definitely need a wiring diagram!

I'd do both of these things before I ordered a new one.

Steve

 

[gene]

Well, here is the latest status report:
I decided to try to start the engine without the stop solenoid in place. I reasoned that by removing the solenoid, I would be assuring that the solenoid plunger/fuel rack shutoff relationship would be taken out of the equation. Guess what; the engine kicked right over and ran until I manually put the fuel rack into the shutoff position.
So......, is there any reason I should not assume that the stop solenoid is bad and replacement is in order?
Couple of other comments related to the wiring schematic diagram. It shows a red/yel wire going from a CR1 relay to "Fuel (hold)" and an orange wire from the starter to "Fuel (pull)"
Any further comments would be appreciated.

 

[Stubbyie]

Good to hear that you are making progress in that you got 'er lit by taking the stop solenoid out of the circuit.

I ''think'' the wires the way you're describing them indicate the circuit flows in a 'loop' in order to get a start: after coming from relay, through solenoid, power is applied to starter. Emphasis on ''think''.

My suspicion is that you have determined that you have a bad stop solenoid. Based on the way way you describe its rapid cycling. I suspect an internal failure of the electromagnetic coil grounding itself. It might be that the cycling is could be caused by an internal dead short and your bench power supply is resetting itself very rapidly each time it shuts off as it sees the short over and over and over. A multimeter across the power supply clips might give you more information.

This may be one of those times--at this point--that you bite the bullet and buy a new part. I'm not a parts-plugger and doing so just bothers the heck out of me--but sometimes your options run out.

I can't recommend going without the solenoid. That shut-off feature could come in mighty handy if you got into a bind.

Please continue posting and let us all know your plan of action and how it all resolves.

 

[Apogee]

The two wires to the two stop solenoid terminals are as follows: The red with yellow stripe wire to the #2 terminal pulls the 12.28 volts and leads from the #2 terminal to one of three relays. The orange wire from the #1 terminal pulls no volts and leads to and ends as a blade connector to a white wire that goes to the starter solenoid.

Gene,

You might be put a multimeter between the two solenoid leads to see if they make contact when the solenoid is sucked in. What I'm wondering about is if there is a disconnect contact in the solenoid that turns off the pull-in coil once it pulls in. The reason they'd do something like this would be if it has two coils, one to pull in, and one to hold in the on (or run) position. Based on your description above, it sounds like it might be the case. If there was a pull in coil cut-off contact in the solenoid, it would cycle EXACTLY as you describe.

Finally, I'm suspicious that you are not seeing voltage on the second wire that comes from the starter. You need to measure to see if you get voltage on that wire while cranking or figure out if it's a ground. If it has voltage at the starter solenoid while cranking or with the key in the run position, and no voltage at the other end, you've got a bad connection someplace.

I agree that I am suspicious of the solenoid based on your description but I still think a service manual and wiring diagram would pay you dividends in troubleshooting the problem.

All voltage checks should be between whichever pin and a good ground on the engine block or neg battery terminal.

Ground checks should measure resistance between the block (or neg batt terminal) and pin you are checking that you think is a ground. If it is a ground, resistance should measure less than 1 ohm.

Again, make sure all the fuses are good. Also the relays, as they are are the cheap things to replace.

Steve

 

[gene]

Hello All,
Thanks for your input. I have a knowledge base of absolute zero as it relates to volts/ohms/amps/multimeters/etc, but will try to do some of the suggested troubleshooting tomorrow. I really appreciate the information I've received. I did attempt to attach the electrical schematic, and a couple of other schematics as they relate to the electrical harness. I have to admit that it's a bit Greek to me, but I'm trying to understand the material as best I can.
Hopefully the attachments have been successfully uploaded.
Thanks again.

 

[gene]

Well....., I checked for continuity between the starter solenoid wire going to the shutdown solenoid and it appeared to be just fine.

I looked on ebay today and saw one shutdown solenoid with the right part number...., and since the auction was ending today, I decided to pick it up for $100 including shipping. Locally, I would have paid $160 plus tax. I'm supposed to receive it on Friday and will let the very helpful forum participants know what happens once it's installed.
I also am going to spend time on the internet trying to pick up some very basic skills in reading and understanding schematics and troubleshooting techniques using the multimeter. I certainly need it.

Stay tuned on Friday!

 

[gene]

Received new stop solenoid today. Couldn't wait to install it. Guess what.....; the new one doesn't work either. So, I'm back to square one. I'll go back over all the wiring suggestions and hopefully find something. Before I installed the new solenoid I connected it to the two wire connector and grounded it and turned on the ignition and the plunger stayed extended and remained so when I momentarily cranked the starter.
And again, the motor starts and runs fine with or without the stop solenoid connected to its electrical connector; as long as I do not have the solenoid installed in its normal operating location. While I am running the engine and I have the solenoid connected and secured to a ground with a set of vice grips, the plunger remains extended and doesn't move whatsoever. So I guess it's an electrical problem and always was.

Just an update......, for the time being.

 

[Sterno]

Just a quick test for you, follow your wire from the solenoid back up to the relay you'd mentioned in an earlier post, pull this relay out and swap it with one of the others in there (they should all be the same type). Good chance it will start.

Relay contacts can corrode when sitting and conduct poorly, not letting enough current flow to energize the solenoid.

 

[Apogee]

Bummer the new solenoid didn't fix it. Worst case, you can always re-ebay it. Makes one wonder if the seller had the same problem with his tractor, bought the solenoid and then found the real problem. Might be worth an email to find out why he was selling it...

Check to make sure the brakes are in the on position and both switches haven't been damaged. It appears that the run circuit cutoff also has the brake switches wired into it. This whole issue might be as simple has not having the parking brake engaged.

Also make sure the blade clutch switch is in the off position as it too is wired into the run circuit.

Not sure what the LN and RN switches are, but they too are wired into the run circuit and you need to make sure they are in the closed position.

All of these are safety switches so be thinking of sitting in the seat, having the blades disengaged, the emergency brake set and any other safety measures in place before trying to start it. The manual likely outlines the starting procedure. Not trying to be condescending in any way. We all get in habits and sometimes forget one of the steps involved. For example, my girlfriend has a zero turn mower. For the life of me I couldn't get the damn thing started. Turned out that both control arms have to be completely at rest, the emergency brake set, and the blade clutch disengaged. So imagine me sitting there with one of the control sticks ever so slightly off it's rest point and it was just enough so it wasn't tripping the safety switch. The point is, I went back to the manual, reviewed the starting sequence and all of the safety stuff and finally figured it out...

In looking at the wiring diagram, the tractor has the seat safety switch wired in as part of the run circuit. I don't know how your specific tractor works, but likely if you leave the seat while the tractor is running it will shut off. Seat switches tend to fail and this might be your problem. Check the switch itself with a meter to make sure it has continuity when you are sitting in the seat. Also check the wires that run to it and make sure the wires are in good shape. If you find one where the insulation has been cut through, then you need to check the fuse that feeds that circuit. You can usually jump the two leads that go to the switch to see if it fixes the issue.

I'd also check fuses and swap the relay as mentioned above. The run circuit is controlled by the CR1 relay. You should find a block with 3 relays in it. The left hand one should be CR1. As mentioned above, all 3 relays are the same. CR1 is the run circuit, CR2 is the clutch circuit, and CR3 is the start circuit. If you pull the middle relay (CR2), and swap it with CR1, the tractor should start and run if it was a bad relay. If the relay is bad, you just won't have the electric clutch.

Finally, if none of the above fixes it, then I'd be checking the key switch. The key switch rivets that hold on the spade lugs tend to corrode if the tractor is exposed to the weather. You might find a corroded contact on the back of the switch and this would likely be your problem. You need to pull the wiring plug off the back of the switch to be able to see it.

Hope this helps!

Good luck,

Steve

 

[Apogee]

Gene,

I just looked up the Lastec 3372. I didn't realize it was a zero turn mower.

Likely the LN and RN switches are at the base of the control sticks (or attached to the linkage) similar to how my girlfriend's mower is configured. I'm guessing if either of the sticks aren't in the "home" position, it likely won't start similar to the scenario I encountered with her mower. You have to figure the Lastec designed it to prevent it from starting and taking off in a circle on somebody when they're not expecting it. There has to be safety interlocks on the controls.

It could be that one of the control sticks or switches is out of adjustment or a switch has failed.

Something else to check.

Steve

 

[gene]

Sterno: Today I purchased a relay and replaced each relay; i.e., CR 1, 2,3, and 4 in turn and none affected the shutoff solenoid plunger which remained in the extended shutdown position.
After doing this, I fashioned a replacement plate to cover and install in the location where the shutoff solenoid is located. (I disconnected and removed the shutoff solenoid from its electrical connector.) As stated before, I was able to start and run the mower and actually went on to mow 4 acres today. Mower started and ran fine. I then manually shut it down with the lever attached to the injector pump.
Steve: Yes, the Lastec is a commercial zero turn mower and operates and has the safety switches exactly as you described. It will not crank unless the brake lever is engaged and the two steering arms are nestled in their cradles. (I have bypassed the seat safety switch a year or so ago.) The blade switch must also be in the unengaged position. I just replaced the ignition switch last year, but will check it out and fuses also, but have not been able locate the fuses as yet. Considering that the mower starts and runs fine when the solenoid is removed from the mower, does that narrow down some of the potential problem areas. Focusing on the wiring to the shutdown solenoid, I've checked the continuity of the orange wire which connects by blade connector to a white wire going to the starter solenoid, it checks out fine. Same is true for the continuity from the red/yellow striped wire that leads to the relay. So, there's no interrupted circuitry from the relay or the starter solenoid. But as I've said before......, I'm out of my comfort zone when it comes to using a multimeter. Any further suggestions would be appreciated.

 

[lsmurphy]

Bypass all safety switches. Wire the solenoid directly to a switch.

Keep life simple.

 

[Apogee]

Gene,

Looking at the schematic there are two circuits, one for starting and a second for the solenoid hold or run. We have to focus on the run circuit.

Need to find the fuses. I can't tell if they are inline holders or if there is a fuse block. I *think* there are 3, one 30 Amp, one 10 Amp and one 2 amp.

I would recommend disconnecting each safety switch one at a time and checking continuity when in the "home" position. In other words, pull off connector on a brake switch for example and make sure each has continuity when the brake it pressed. Do the same with the safety switch on each control stick. You will just have to work your way through the system one switch at a time until you find one that is either out of adjustment or not making contact because it has failed.

Honestly, as much as I dislike the safety interlocks, they are there for a reason. I'm a much bigger fan of fixing the problem rather than just bypassing everything.

Glad you were able to get your mowing done. You are going to be an expert on this thing like it or not once you're done!

Good luck,

Steve

 

[gene]

On top on everything, I've come down with a nasty cold. I'll get back to let you know, once I shake this cold. Could be a couple of days.

 

[gene]

Eureka! Finally got over the nasty cold and went back to work on the shutdown solenoid problem. Based on the circuitry suggestions I again tested the continuity from one of the shutdown solenoid contacts via an orange wire back toward the starter solenoid. The continuity was fine for the orange wire, but just short of the starter solenoid it attached by a blade connection to a 6" white wire which, in turn, connected directly to the starter solenoid. When I checked the continuity in the short white wire, I found none. I replaced the 6" white wire and hooked everything up (without reinstalling the shutdown solenoid) and noticed that the shutdown solenoid plunger retracted when the engine was cranked. So....., problem solved!!
THANKS SO MUCH TO EVERYONE. And Steve/Apogee, you are now finally released to begin helping others on the site!

 

[Apogee]

Nice work Gene!

I'm guessing that white wire might have been a fusible link. It could be that your unit doesn't actually have fuses but instead uses fusible links for protection. That white wire might have an amperage rating on it. If so, you might consider replacing like for like. It will work fine with normal wire there, but be mindful that you might not have protection if a short occurs. You can also get around this issue by adding an inline fuse to the circuit. Again, only necessary if there is no fusebox.

Glad it's fixed.

Great job,

Steve

 

[gene]

Steve,
I never even considered a fusible link; it just looked like a common wire to me and I just went through a few spools of wire and chose what looks like a 14 or 16 gauge braided wire. I'm going to take the one I took off over to the Kubota dealership and check to see if it could be a link and get a replacement if it is. I'll take the schematic with me. Thanks so much for your help; it's truly been a learning experience for me. And..., based on what you say, it may not be over yet.
Gene

 

[Apogee]

Gene,

You might consider giving Lastec a call regarding that wire. I'm guessing Lastec would have more info as they would know more about how they wired it than Kubota.

They would also be able to tell you where to look for the fusebox if it has one.

Just a thought.

Steve