Hea guys, I own an automotive shop we do not normally work on lawnmowers. I had a customer ask me to look at his Kubota Zero Turn K725 Kh with Kohler CV742-3011. The dealership would not touch this. He came in with a wiring issue. Here is what we found there was no spark, and the diode was bad and some bad relay, and the COD box was also. The other rectifier was bad and the starter was stuck in the start position. We purchased the cod box and some relays. Kuboat did not show a part number for the Diode so we `used a GM diode that fit in a small fuse holder.. After all this testing of continuity and making sure it all checks we tried to start no such luck . So I hot-wired it and found we had no spark at the plugs. so we test the sensors on the motor. We found the oil switch it also the kill switch so we replaced that It still will not start at the key but will turn over when jumping it. we have plenty of sparks but the motor will not run. We have replaced the start switch and tested it it works. I fit to be tied at trying to get the **** thing running. Any help would be greatly appreciated
K725KH no start
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whitetiger
Moderator
Staff member
Equipment
Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
Here is the start circuit schematic for a Z725 which I think is the model you are tinkering with. There is no such model as K725.
If you have spark, test for power at the fuel solenoid (located on the carburetor I think). Once you have spark and fuel, it should start.
I have a Toro with a Kohler Engine. I always find Kohler's web site is very useful when it comes to no start situations.
Kohler CV742 service manual
Kohler recommends you break the connector which ties the engine to the equipment. In that connector is a white wire which is the 'KILL" wire for the engine. You remove the white wire from the connector and replug it together. Now try and start the equipment.
If the engine starts you now know the problem is with the equipment and not the engine.
Of course now you cannot stop the engine without shorting the white wire which was on the engine side of the connector.
From page 34 in the WSM for your engine:
Dave
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
May (probably ..) need to remove the fuel solenoid and clean it. Have done several over the years as they're
prone to 'stick shut' even with power to them.
I recall they are pricey and one bodge is to just remove the rubber and install an inline shutoff.
prone to 'stick shut' even with power to them.
I recall they are pricey and one bodge is to just remove the rubber and install an inline shutoff.
We tried this and does not work. Thanks. We hot wire it and the motor will turn over and have a spark. It will not fire even when adding starting fluid. The key will not turn the motor over either. I going to try the fuel solenoid on this carb to see if that works. Still confused with all the stuff we tested and replaced at the factory parts.
This one is screwed into the 2-barrel carb. with a red and black wire connecting it to the wiring system. Would that be the reason for the key switch not working? I can have the key on the turn the motor over with a hot wire. I'm getting spark but when I spray starting fluid is still do not get this to run. Thanks for your help
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
if you have spark and 'fuel' in the intake.... that only leaves timing.
key between crankshaft and flywheel could be sheared or 'mushed'....
Pop the blower off the flywheel and see if the key is 'square' int he keyways
key between crankshaft and flywheel could be sheared or 'mushed'....
Pop the blower off the flywheel and see if the key is 'square' int he keyways
Rag stuffed in exhaust by mischievous kid or mud dauber nest in exhaust. Bent,broke,loose valve train component. Cracked head,block,ring or piston,blown head gasket causing poor/no compression. Weak spark (yes it's not uncommon to have spark present but inadequate). The list is endless but mechanics (auto or otherwise) usually take a systematic troubleshooting approach to process of elimination for these who-done-its.
Have you had the spark plugs out to make sure the spark is getting there? You could pour a little gas in there while they're out.
We did all the continuity tests on each wire switch relay and sensors or even an ohms check. I know kids have never touched this. Even check the diode it was faulty and replaced. The wiring is a night mare i rather rewire a semi of a car versus this Kubotoa
That's a fact which I've brought up here on more than one occasion. Kubota dealer techs can't even figure out the Rube Goldberg figit-bits and wiring so they just replace the accessories and harness.. Did you not mention earlier that dealer refused to take the job?
If you followed Kohler's instructions and their motor does not work, this means in their world you have determined the problem lies with the motor so stop checking anything on the machine.
Did you download and read the Kohler WSM that I provided the link for?
What happened when you removed the white wire from the connector and reconnected it? You said "does not work," but this could mean many things to forum members trying to help you.
The engine WSM is important as it will have a step by step diagnosis process which saves a lot of time and needless parts changing.
Dave
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
at the risk of repeating myself, these are simple machines...
NOT a wiring issue, as he has spark...
Pull plugs, squirt some gas in both holes, replace plugs, 'start' engine...
If it doesn't cough, bang, fart after 30 seconds.....remove blower fan, look at the key.
These are simple machines. They need 3 things...
1 ) spark..yes
2 ) gas..yes
3 ) timing...??
Please report back when you look at #3.
NOT a wiring issue, as he has spark...
Pull plugs, squirt some gas in both holes, replace plugs, 'start' engine...
If it doesn't cough, bang, fart after 30 seconds.....remove blower fan, look at the key.
These are simple machines. They need 3 things...
1 ) spark..yes
2 ) gas..yes
3 ) timing...??
Please report back when you look at #3.
I have the Service manual on my desk it's in a binder after I printed it, The white wire is the kill wire that runs through the oil pressure switch or sensor. If this sensor is bad I will cause no spark issues the sensor is normally closed during the startup operation. We ohm checked it and it was fluctuating from 0 ohms to 20 ohms. So we replace it with new factory one. As for the timing, I did try to move the flywheel and did check the end play. But it was still factory-tight the rust around the shaft and bolt did not show any new metal scars. So all this told me that the key was still in place.
Simple machine Answer The wiring is not simple. It has four wires for a redundant system on the zero turns, The seat switch has four wires going to it. The Parking brake also has four wires for the same redundancy.
YOUR statement SIMPLE MACHINES. No, my push mower is a simple machine HOLD down BRAKE PULL THE ROPE IT FIRES. This is a simple machine.
The wiring is not simple. It has four wires for a redundant system on the zero turns, The seat switch has four wires going to it, and The Parking brake. It has four relays three of which are safety systems for this mower. then we add that timer delay to the mix. It is very easy to make the mower safe with fewer systems that can malfunction. I do appreciate your help but I have been working on cars since I was 14. I rewired a Polaris GEM 2 Electric golf cart, we worked on a Polaris 4X4 with ignition box troubles. I have been reading wiring diagrams for a long time and know how to test systems.
Don't get me wrong but I tried a lot of things that the manual has stated. I use my spark gap test to check the spark in a very good range. The only thing I have not checked is the fuel sensor in the carburetor.
I do have a concern that PTO is not kicking on. This is a new problem that my customer had stated. If you pull the PTO button it makes no sound. Could this also be the issue for no start trying to use the Key to start this?
I do thank everyone for the helpful advice
The wiring is not simple. It has four wires for a redundant system on the zero turns, The seat switch has four wires going to it, and The Parking brake. It has four relays three of which are safety systems for this mower. then we add that timer delay to the mix. It is very easy to make the mower safe with fewer systems that can malfunction. I do appreciate your help but I have been working on cars since I was 14. I rewired a Polaris GEM 2 Electric golf cart, we worked on a Polaris 4X4 with ignition box troubles. I have been reading wiring diagrams for a long time and know how to test systems.
Don't get me wrong but I tried a lot of things that the manual has stated. I use my spark gap test to check the spark in a very good range. The only thing I have not checked is the fuel sensor in the carburetor.
I do have a concern that PTO is not kicking on. This is a new problem that my customer had stated. If you pull the PTO button it makes no sound. Could this also be the issue for no start trying to use the Key to start this?
I do thank everyone for the helpful advice
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whitetiger
Moderator
Staff member
Equipment
Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
The wiring on this unit is so simple that a Kubota tech can understand it.
Actually, this is one of the simplest wiring diagrams for a zero-turn mower I have ever used.
Here is a pdf of both the early and later production units.
Actually, this is one of the simplest wiring diagrams for a zero-turn mower I have ever used.
Here is a pdf of both the early and later production units.