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Danstar · Jul 16, 2009, 07:11 AM

I have a Craftsman lawn tractor Kohler 15.5 HP engine. (Nine years old, like new)

Will not cold start late in the day when its hot outside "80 Plus"

It gets plenty of gas , turn over well, No vacuum lock in gas tank, however no spark.

When the outside temp cools off, it runs and starts just fine.

It started this spring when it got hot in April, then it's been cool the next few months and it started great. Now in July its hot and not starting again.

I took it to a lawn mower repair shop in May, started every time, however it was cool outside?
Sound Crazy?

crigby · Jul 16, 2009, 08:16 AM

Hi,
The "no fire" part has me a bit mystified, unless the engine had been running and shut off. The standard way of checking an electronic ignition on a vertical crankshaft engine is to run it under load for at least twenty minutes, shut it down and check the ignotion after three minutes. That give the heat just the right amount of time to rise and heat the module to make it fail.
One ting I have found with hot weather and Kohler Command engines is they need choke, but barely. My way of starting them in hot weather is to put it on choke to begin with but to take it off once the engine spins a turn. The EPA made sure it was needed, but almost none is neede hot.
Peace,
Clarke

Danstar · Jul 17, 2009, 07:19 AM

Well,
I'm going to go over the starting system this weekend. Check all the wiring. It going to be hot, so the problem start should happen.
I thinking if the engine it turning over good and I'm getting gas, it not one of the safety switches. That would kill everything.
What would effect the lack of spark?

Dan

crigby · Jul 17, 2009, 05:38 PM

Hi,
I must admit to bieng puzzled how you cannot have fire at 80, when it usually 300. Consumer machines do not generally have systems to defeat the ignotion or fuel. That commonly shows up on commercial machines. Most of the time if it spins over, the switches atr working. The only one in that scenario is the key switch itself; which is not heat-sesnstive.
Peace,
Clarke

Danstar · Jul 20, 2009, 07:33 AM

Hi ,
I guess you misunderstood me, I was not talking about inside the cylinder temp. I was talking about the out side Air temp.
Sunday Morning it was 68 degrees out side , It started and ran well for an hour and a half, the time it take to cut the lawn.
I even turned it off and restarted twice during that time.

However, Friday late afternoon it was hot, About 87 degrees out side and it would not start.

crigby · Jul 20, 2009, 07:54 AM

Hi,
No I understood that you were speaking of ambient temperature. I just never seen it with a Kohler if it was not a flooded situation; and I have seen it probably over one hundred times.
I described one way to crank. That works with some people. The other way I have shown is to get the engine turning over and then to push the throttle to choke for a split second.
Peace,
Clarke