Kohler will not start

[tsimm1]

I have a 27 HP Kohler Model CV 740 engine retrofitted into a Poulan 48 Inch mower.It originally had a 25 Hp Briggs,and the replacement engine had a modified wiring harness connector to interface with the Poulan.Everything ran fine, till I replaced a mower deck belt.After that, it would not start.Motor turns over, but will not start.Starting fluid does not help. There is no fire at spark plugs. I checked all wiring,and the KILL circuit for the Kohler is good( White Wire) (not grounded) if clutch is depressed, and seat switch is made, and PTO is disengaged,so safety circuits are being satisfied.I suspect the DSAI Ignition units are bad, but I cant imagine why both would go bad at same time,no fire to either spark plug.
Is it normal for both coils to go bad at same time? Is there some circuit that I am missing that would inhibit the ignition modules?
The SPEC# CV740-0040 Coil= 625840-5 (or S ).
I hate to buy the coils if there is something else wrong.
Any help is appreciated on this matter.

 

[Carscw]

Disconnect the coil kill wire and give it a try.

Sent from my iPhone using LMF

 

[tsimm1]

Disconnect the coil kill wire and give it a try.

Sent from my iPhone using LMF

Already tried that, still no firing of plugs.The kill wire is the white wire in the connector from engine.It is not grounded(clear).

 

[ILENGINE]

Kohler has had problems with voltage spikes frying the modules, If there is not a clampling diode between the leads off the electric clutch it can cause a voltage spike when the clutch is turned off. There has also been cases where jump starting the engine, then disconnecting the leads that where connected to a dead battery has fried the modules.

Kohler says the black wire is the engine kill wire and not the white. the red lead should have 12 v with the key on, when tested at the ignition module. Kohler tested for the DSAI is to remove the blower housing disconnect the leads on the modules, make sure the connections are clean. Check for continuity on the black lead to a good engine ground with the key off. Should have continuity. Then turn the key on at check for 12v on the read wire. If those two test pass, then replace the modules.

And if the electric clutch doesn't have the clamping diode then you need to install one.

 

[tsimm1]

True, the wire on the module itself is black, but it changes to white at the connector for the chassis wiring.This is the white wire to which I referred.It is not grounded till the switch is turned off, or a safety interlock is tripped.Refer to KohlerEngines.com,wiring diagram 24 690 07 revision C. If there is a newer revision ,please direct me to it.
I will double check the connections, and continuity of all wiring.
CRAP like this ignition makes me long for the good old days of points and condenser.They gave a lot less trouble,and the new stuff does not improve anything except the profit of the company that sells the spare parts.
Kohler is a disappointment,and proof that corporate greed has overcome the desire to make a durable, robust,long lasting product.
A 1N4002 diode costs less than a nickle to add to the circuit.And look at the trouble it might have saved.Of course, a nickle times many thousands of motors will pay for your greens fees.Of course, this is just my opinion, I could be wrong,however,I will never make the mistake again of buying one of their engines.I bought this one based on their previous reputation from many years ago.
RIP: Grandpa's Kohler.
Thank you for your help.::smile:

 

[Rivets]

Not having the diode in the system is not Kohler's job. Poulan installed the electric clutch, they should have added the diode. Make sure you are blaming the right person or company.

 

[tsimm1]

I have been an electronics engineer for over 50 years, before CMOS,during the vacuum tube days.I have designed circuits using all current technologies as they advanced thru the decades.An engineer that would design a static sensitive or spike sensitive circuit without protection is obviously under pressure from the accounting department or he is not really an engineer to begin with.I tend to believe the former. I have been there,but refused to do that.I have had many career changes because I would not compromise good design principles to save a few pennies.Pass the buck is their motto, but in this case, pass the pennies.
As I said, it would only cost pennies to add the diode at the manufacturer stage,and it would not hurt if Poulan and Kohler added it.A little redundancy would be nice, but then again, the executives might have to forgo a round or two of golf if they spent that penny.
I have modified the standard circuit to incorporate surge protection, flyback (CEMF) protection,static protection,and overload protection,all with spare parts I had lying around.New cost of the components, at consumer prices was less than 25 cents.In bulk, about 2.5cents.
Kohler is not the only company that does this, I have repaired automatic transmission control computers that suffered from the same problems,and I always add a free wheeling diode to prevent repeat failure.It is a sad statement on corporate greed when disconnecting a battery can destroy an expensive module.
Perhaps I am just an old dinosaur that has outlived his time,and it is time for the new throw-away society to have it's day in the sunshine.Sooner or later, you will run out of "stuff", and the landfills will runneth over.

 

[ILENGINE]

Kohler added diodes (2) to the wiring harness awhile back, and the electric clutches were not only frying the diodes but was still getting the modules. Even had one case on an EFI engine, where the tech had his laptop connected to the ECU diagnosing a problem, and when they shut the electric clutch off, acts like a generator when winding down, not only did it fry the ECU, it also fried the guys laptop.

The new DSAI modules are supposed to be designed to withstand more of a power surge situation, and have removed the diodes from the wiring harness. But still require the PTO clamping diode for added protection.

 

[tsimm1]

This engine is a 2002, and I do not see any additions to the wiring harness.In view of your feedback, I will change the diode to a higher rating,an SK7091, which is a 1000volt 6 amp diode.I will also install the same diodes across the fuel shut-off solenoid coil and the operator presence relay, and the starter solenoid coil.This takes care of all coils (4) that I see in the circuit.
I will also install an MOV,15 volt,(#2V015)in series with a 5amp fuse,from battery Positive to ground,in the harness,so it will be present when battery is connected or removed.This will arrest any voltage spikes when battery cables are connected or disconnected.The MOV is a one-shot device, and it protects by Crow-Barring the supply very quickly,if it exceeds the rated voltage, thousands of times faster than a fuse, so the fuse is in there to prevent melt down if the MOV fails in a shorted mode..I will install a small indicator lamp or LED across the fuse to indicate when it has failedlight on=failure=replace MOV) Most of the time the MOV's protect and fail, then go open, with no visible indication,so the indicator is necessary.
Maybe with these additional modifications I can get good service life from this engine.
My first riding mower was a tricycle type, tubular frame,semi-pneumatic tires, a belt clutch, and a 36 inch cut.single speed,just forward and reverse.Gearbox, not a transaxle. It had a 5hp Briggs engine, and it would cut tall grass the full width with no problem.
So when I upgraded to an 8hp, I was disappointed,it could barely cut the 40 inch width.Then I went to a 10 Hp, and it would strain trying to cut the 42 inch width.I began to suspect that someone was fudging the HP numbers, and sure enough, my suspicions were true.Now they only state TORQUE,not HP of their engines.
The last good HONESTLY rated small engine I remember was a 1986 horizontal shaft Briggs 16 HP. I still have it, and it runs good.A single cylinder in an MTD frame, that was made before MTD had it's own brand on the market.It was sold by JC Penny,had hydrostatic drive,hydraulic lift,came with a snow plow and road scraper blade.It had a driveshaft to a gear-box on the mower deck that drove the mower belts.I have had very little trouble with this machine,replaced 1 axle seal,rebuilt front axles by replacing them with boat trailer spindles with bearing-buddies, one set of rings, a head gasket, carb kit, and that is it.Almost 30 years service, and still going strong.
It will still outperform the 27 HP Kohler any day.It had a 50 inch cut, and didn't slow down in heavy pasture grass.The Kohler has a 48 inch cut, and stalls if you go too fast.
Wish somebody still made them the way the Briggs was made back then.
(sigh).

 

[SeniorCitizen]

How long must we put up with this squirrel ?