Kohler command 25hp backfiring when warm......

[selph]

It runs about 20-30 minutes and then starts backfiring really bad. It does it worse the more throttle that you give it. I have changed plugs, air filter, battery, cables, fuel filter, cleaned the carb, and cleaned all electrical connectors. On the old engines, i would have said that it was a condensor. Could it be the coil? It runs great until it heats up. It has the smart spark. Is this warranteed by Kohler? It is a 1997 model with 115 hours. I have no idea on this.... Here are the numbers:

FAM: SKH25U1GZRA
Model: CH25S
SPEC: 68562


I don't know if it has anything to do with it, but most of the time (not all), it seems to happen after putting the parking brake on or turning the lights on. I cleaned all of the connectors though.

Thanks for any help! Dave

[mud_man93]

your problem could be a a safty switch or it could be a bad spark plug wire hope this helps

[selph]

It did it last week and I cleaned all of the connectors. After I cleaned the connector for the parking brake, it seemed to run fine. I tried it today after it started acting up and it didn't help. I did get a shock from one of the plug wires trying to check for spark with the engine running. Dave

[selph]

Doesn't anyone else have any ideas? Is the smart spark under warranty? It is 4 years old with 115 hours on it. Thanks! Dave

[Jman]

The smart spark ignition on the twin cylinder engine does carry a lifetime warranty on parts and labor.

[LeoS818]

Is the battery staying charged up?

[khouse]

jman is right - get that smart spark module changed out. Once your engine warms up the components expand in the module and opens up circuits. After you cool it down it works fine.

[ohiolawnguy]

i remember on our old 23 hp kohler on our 61" ZTR, we had a similar problem. the dealer replaced a part he referred to as an anti backfire solenoid. that might be the same as the smart packmodule, but im not sure. as i was explained, this anti backfire slenoid is installed because the machine is supposed to be turned of at full throttle, and whithout it, it would backfire each time you turn t off..

[selph]

well....hare is an update....I took it to a dealer and they (reluctantly) changed out the smart spark module. They also checked the coils to make sure that they were good. I picked it up and brought it home. It mowed the yard (a couple acres) just fine. It was cool outside. I tried to mow again today and it ran about 20 minutes and started backfiring again really bad. It is pretty hot outside today. Any more ideas? Thanks! Dave

[khouse]

you may have a bad coil. it would check fine until it heats up then break down. Sorry it wasn't the module.....

[selph]

Is there a good place to order a coil online? Thanks, Dave

[grasmo]

first i would do a compression test. cold and then hot. if the readings go down considerably when its hot i might look for a bad valve. or it could be to tight. engine heats up valve expands and gets held off the seat causing backfire. grasmo.