30hp Kohler random insanity

[Timbersawz]

CH750 30hp v twin kohler that runs one of my chippers is randomly cutting out like its been switched off. Then it starts right back up. Sometimes it does it again after a minute, sometime after an hour, its very random and hard to isolate or replicate.

When it does cut out the chippers cutting wheel turns the engine for a while until I disengage the clutch, and you can start the engine normally by turning the key back on and the turning motor would fire up, but in this case, if the engines died it wont "roll start" off the turning cutting wheel if I turn the ignition off then on. But will fire up on the keystart,

When it does cut out, and the chippers still turning the engine at about 2500rpm if I stick my digital tuning tach on the sparkplug is shows 0 rpm so im starting to think its an electrical problem. I have changed the oil and filter and fuel filter.

Any ideas????? its driving me nuts

 

[bobmisi]

Any time that I have had a problem such as you're having, it turned out to be the coil or a loose wire (either a hot wire or a ground.) Could possibly a bad switch also.

 

[J_J]

If the carb has the solenoid in the bottom or side of the carb, remove it and inspect for proper operation, clean and or replace.

Also check for loose wires or frayed wires.

Check that grounding wire to see if it is flopping around.

Check the switch, or bypass the switch.

http://www.kohlerengines.com/onlinecatalog/pdf/sm_24_690_06.pdf

Look at your wiring. Kill wire is wire U connected to wire D from the ign module.

 

[Baby Grand]

Something in the gas tank randomlly getting sucked onto and blocking the supply port to the carb?

 

[BKBoiss]

I had a honda on my portable air compressor doing almost the same thing, it would die then not want to start then run again I was convinced it was a carb or fuel problem until I got so completely frustrated I changed the coil? Not sure if that's the right name but the piece that runs off the flywheel and makes the spark. Been working fine ever since. Same thing with our 1800 Oliver would run then quit and not start and so on. Spark tested fine and long story short after LOTS of messing around changed the coil just because and presto. That being said maybe the key is wore out and losing contact or something like that???

 

[Timbersawz]

I was really pulling my hair out over this initially as it was hard to tell if it was fuel or electrical. I removed the needle and spring from the carb solenoid and it didnt change the machine at all aside from some rather epic backfires!

I have since been able to use a tach on the plug lead when it was in the process of dying, and although the engines still turned on and being turned over at about 2000rpm by the momentum of the chippers cutting wheel, there is a zero rpm reading. So I assuming its a spark related issue as even without fuel the engine being turned on and being turned over at that RPM should still spark. (right?)

The most annoying bit is that it does it so randomly, so trying to track down the fault without throwing lots of money at uneeded parts (im in NZ and just the starter is over 500 us dollars).

Usually with coil problems they dont like starting afterwards and tend to die like they are out of gas, but this has no trouble in restarting and it doesnt seem to happen after x amount of time. Not saying its not the coil but to me its like its totally shut off somehow. but will explore that direction as well as ignition system and key

 

[The Fred]

IF the engine has an oil pressure switch for the automatic shutdown function it might be closing on you thus shutting down the engine, it is fairly common.

It WILL kill the spark when it closes acting like the engine has lost oil pressure. The sensor is "C" on page 30 of Mr. JJs attachment. Also "B" on page 34 of the wiring diagram.

Good luck, Fred

JJ you are the man.

 

[kencunningham]

If this engine is equiped with a low oil shut off, unhook the sender the next time it does it. Worth a shot, and it wont cost anything to try.

 

[Timbersawz]

IF the engine has an oil pressure switch for the automatic shutdown function it might be closing on you thus shutting down the engine, it is fairly common.

It WILL kill the spark when it closes acting like the engine has lost oil pressure. The sensor is "C" on page 30 of Mr. JJs attachment. Also "B" on page 34 of the wiring diagram.

Good luck, Fred

JJ you are the man.

JJ is awesome, I have searched all sorts of threads on here and find his info very good. Thanks JJ

You should have seen the leaping for joy I did when I discovered the fault today. after the chipper died for a 8th time within an hour, I leaned over the engine to reach my tachometer (the engine was still being turned over by the cutting wheel) and it came back to life.
The key ignition must have taking some sort of hit at some time, and even if turned on, if the key gets into a certain position it cuts the engine. I had tried turning the key on and off when it was cutting out but what I needed to do was push it inwards and slightly up. Leaning on it had done this and got it back to life.

So a new ignition and it should be all good. Thanks guys for the help, this is my second ch750 I have had issues with.