kohler cv740 still dieing

any body got suggest pull what little hair left out on this unit, runs smooth as can be for couple hrs then just stop like turn key off, fires right back up with out choke then re die, did so far, fuel tank been flushed, all new lines,new coils, even tried new carb, still flunked. only thing i have not switched or touched is piston and valves. going to try tomorrow with out muffler see if it is perhaps exahust valve stick, i am out of ideas. this is twin so when it dies it never coughs, pops or anything just like turn key off. and it is very picking on time lenght last winter when had thought fixed it ran for 6 hrs befor just died, talked kohler expert techs and they stumped said call back when i found what it finall was. anybody got geuss on this one.
 
done that ,switched caps even ran unit off my test stand fuel tanks and ran till tanks were empty thought had it then about hour into second tank fill it died!!!!
 
Since it is a twin, both exhaust valves would have to stick.

Is there an electrical connection somewhere that gets loose or wire broken inside the insulation? With it running try wiggling all the wires and connections/connectors.

Is there an overheat switch anywhere on the engine?
 
i agree on the valves its got me stumped. been ther done that with the wiring,have unhooked electric clutch also see if would change same results. muffler gets red seem like aawful quick is only thing i can pick up different, done leakdown, relays, fuses, switches, alll tried , replaced modules,new regulator. charge ssystem specs out. switched complete carbs with different unit same result, that why keep coming back to wiring. but be d!!!m if solve it yet.keep quessing
 
My hair and nerves are about gone. I have one doing the same thing. Customer can mow his pasture with no problem one day. Can't get ten feet the next.I have checked everything but the paint.Let me know what you find.
 
Does it have a mechanical fuel pump in the valve cover? I've seen one old one that would run fine for hours sometimes, but suddenly quit pumping.

When it quits, do you still have 12v. on the fuel solenoid wire at the carburetor?

Check the plug between the chassis and the engine wiring harness. I've seen loose connections there cause some pretty strange problems.

The Command engine has hydraulic valve lifters, so I do not think you would lose compression on both sides at once.
 
If eng has an oil pressure sw try disconnecting and see if that cures problem,you may have a bad sw or plugged/restricted filter,worn oil pump,sticking relief valve,excessive wear of internal parts causeing a loss of oil pressure when eng gets hot,you must have a min of 3# pressure to keep pressure sw conacts open otherwise they will close & kill ign if pressure sw being used for a safety shutdown rather than lighting a low oil light.

Also check around on head/under sheetmetal covers,some model's of the CV series eng had a high temp washer style sw under one of the head bolts with a quick disconnect terminal on same,if you find on your eng disconnect same & see if it helps.
 
yes still have voltage on fuelsolenoid wire, i even bypassed harness wire with seperatate direct to solenoid on carb,same result. but it will fire right back up with no choke!!!!!! agree its twin so should not total die if valve issue. we have had harness out two three times no luck. still same result try again!!!!
 
did that, had muffler off several times can not find anything, have check the bolts on manifold etc, going try run with out muffler see if anything happens. but yes have done what you suggested. any other guesses rick thanks
 
joe, thought that two but when warm would it start immediately back up,cause it does,going check for your second paragraph switch but sure don,t remember wire there, this unit was last touched last winter getting it back out now to try again customer will be chomping at the bit. he has been using loaner so he can't bit!!h to much. rick
 
Does your engine have the Smartspark module on the blower cover? I know you said you changed the coils. I am also thinking the Kohler coil kit does away with the Smartspark module.

If its still on there, it might pay to swap it for a known good one and see what happens.
 
What brand & weight Oil do you use?
How many hours are on the motor?
What brand mower is it being used in?
What brand oil filter is being used?
When the motor dies do you still have
spark at the spark plugs?
Does your engine Oil Sentry?
 
kohler oil 30wt/10w30, motor hrs little over 400,woods mow machine 61 inch,kohler oil filter,yes
it fires right back up,switched that oil sentry.still need help cause it still doing it you just
don't know when it will die ,be it days or hr. i still know it some little simple thing but
boy!!!!!
 


Do you know if there is spark as the engine dies?
Just curious what spark plugs and number are you running?
Could you send a picture of the plugs?
Have you checked the Flywheel Key if it is possibly partially sheared?
Please Email all Numbers from both the engine:
Model
Spec.
Serial
Rider:
Model
Serial
I live very close to Kohler and know many people there.
I will do my best to try and help you.
Later, Bob
 

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