Craftsman Tractor with 15hp Kohler Command Problems

[Harlan]

Got one of these to "fix" for a friend. 917.256550 CV15S Kohler Command. It was running fine, then he intentionally shut it off for about 5 minutes, then upon trying to restart, all ****** broke loose: backfiring, hard starting, won't stay running for more then 2 seconds.
Now it won't start/run at all, and every-so often will get a "pop", then that's it. Its a gravity feed gas tank, and has fuel to carb. Pulled the valve cover off and pushrods, rockers, and valves move. No broken valve springs. Cylinder has compression. Flywheel key wasn't sheared, and magnet is secure to the flywheel.

I'm going to dig into it this weekend. Seems like timing or spark....Any hints where to look?

Thanks,
Harlan

[Bill Kapaun]

Timing is controlled by the flywheel position, so if the key isn't broken, the timing should be good..
I'd GUESS ignition coil?

[Harlan]

Spark is hot and good. I have a spare working coil off a running engine, and still same symptoms. Somebody said something about the ACR?

[Tractor-Holic]

I think you mean the "chip" that retards and advances the spark,if it has one??..some Kohlers do..looks like a small relay..

an "ACR" is a "automatic compression release" ,and thats operated by a flyweight on the camshaft,that holds one valve slightly open at cranking speeds to releieve some compression--its doubtfull even if its spring failed that it would affect the valves once its running over 200 rpms..

There is another thread about the spark timing chip on the "Small Engine Repair" forum I believe..I'm wondering if my 20 HP Kohler Magnum has oe,its been driving me batty with "undiagnoseable" stalling symptoms..it'll run absolutely perfect one minute,and do so anywhere from a few minutes to hours,then it stalls out like it ran out of gas--still has good spark,and even dumping gas down the carb dont always get it to restart,if it does it only runs maybe 5-10 seconds..let it cool off a few hours and it restarts instantly and repeats the same scenario..I'm ready to take a sledge to it!.

[Harlan]

Didn't notice a small relay looking thing.
Now it won't even pop or backfire when trying to start. I've shot starting fluid down the carb, and still nothing....

[Bill Kapaun]

Did you check the spark with an actual spark plug tester?
You can have a spark under atmospheric pressure, but under engine compression you may not.
If nothing else, grab an old spark plug and open the gap to around 3/16" or so and see if the spark will jump that.

You might also try "priming" the carb with a tablespoon's worth of gas and see if it fires on that.

[Harlan]

Yes.
I have one of those clamp on adjustable spark testers. The gap was 1/4" and spark was hot.
I sprayed starting fluid down the mouth of the carb and still nothing...

[kcp877]

I had a similar problem, couldn't get the engine to fire on fluid, had spark, timing good etc..

Here's how i got it going. Removed the fuel line, spark plug and carb bowl, , removed the air filter. Drain the gas tank into another container.

crank the engine over to clear the chamber and the carb of anything in there. Make sure your plug is good, hook it up and make sure it's sparking out of the engine. I would imagine when you pull it its going to be soaked like mine was, but still firing just not starting the engine.

Now, put the plug back in, give it a good shot of carb cleaner, put the choke on and hit the key, mine still took a good 3 tries, then pow, fired, i ran it like this for a few squirts before shutting it down. Put the carb back together, put in a little gas and let the fresh gas clear out the fuel line and filter, hook it all back up.

What I figured happened to mine was some water got in the gas somehow, i think it was water, the tank had fresh gas it in, I put it in, but somehow it got in the carb and was keeping it from starting. I spend hours chasing wires, checking valves, timing, checked the key twice, etc... For whatever reason it wouldn't start on fluid with the carb bowl on and all hooked up, but as soon as the carb bowl was off and the chamber was clear it fired. It starts in half a second now and runs perfect.

May not work, but it's worth a shot and takes only a few minutes. Also, I couldn't even get a pop out of it, it would turn over, I almost junked the engine I thought the guy sold me a junk engine because I couldnt find anything wrong

[Harlan]

Removed the solenoid on the bottom of the carb, and dropped the bowl. Bowl was spottless. Solenoid moved freely with key on.

I had an older 14.5hp Kohler off another Craftsman that was a drop in swap. Didn't even drain the tank, just put the engine in, and it fired on about the third rotation, so I don't believe fuel was the issue.
I gave everything back to my friend, along with the other non-working engine in a milk crate.
I'm too busy, and he was going to tinker with it.

Should have replaced the steering sector while I had his engine out, but didn't have one "in stock"....