View Full Version : kawasaki 21hp poor running in hot weather

07-05-2001, 08:35 PM
Has anyone experienced problems in very hot weather?
My exmark with a 21 hp kawasaki will start and run great until I turn it off after mowing several homes. After it sits in my enclosed trailer to be moved to the next job site and is restarted it will almost stall or will run erratically,then it smooths out and will run fine. The carb was disassembled and was clean,no water in the fuel,and the cooling fins are clean. Recently it now does this first thing in the morning when the engine has only run for one minute and isn't even hot. Any ideas?

Premo Services
07-06-2001, 11:17 PM
I have the 17 hp kawasaki, and it was doing the same thing yours is doing. A mower mechanic told me that I probally had the gas cap on too tight, vapor lock, and should not have it too tight. I loosened it and have never had the problem since. Don`t know if it will work for you , but it worked for me.

Eric ELM
07-08-2001, 05:43 PM
Most air cooled engines don't run their best in hot temperatures. Trying to cool them down with close to 100 degree air just doesn't work as good as when it's in the 70's. It does sound like vapor lock.

07-08-2001, 07:08 PM
One Hint here is to run higher octane fuel in it this time of year, this cools the motor off some.

07-09-2001, 09:58 PM
I agree, I think it has to do with the gas cap also. It probably has a knob on top of the cap. Just release it.

08-12-2001, 03:12 PM
As the problem got worse I removed the fairly new spark plugs and noticed the left one was black. I replaced both plugs and still had the same ocasional sputter or misfire. I checked the
compression and rechecked the carb and found nothing wrong.
I decided to take an educated guess and replaced the left
side ignition coil. It has run perfect ever since. I guess when the coil got hot enough, it would cause the misfire.

Thanks to all that helped!