Craftsman 42" Riding Mower will not start when hot. Starts hreat when cold

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  #1  
Old 04-01-11, 07:56 PM
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Craftsman 42" Riding Mower will not start when hot. Starts hreat when cold

I have a Craftsman 19.5 hp twin cylinder B&S lawnmower that will not start when it is still hot from running. It starts great when cold. It turns over just fine until the battery runs down, which takes a while. Not a battery problem. I have to let it sit for a long time to cool off before it will start again.
 
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Old 04-01-11, 08:00 PM
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chuckalm

I forgot to mention that I am aware of all of the safety switches and they are also not the problem.
 
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Old 04-01-11, 09:35 PM
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When it is running and it's at operating temperature does it behave strangely? Does it stall or lose power under load?

My 1st thought when I read your post was a clogged fuel line,,, or possibly restricted intake or exhaust,,, while any of those would produce the symptoms you've laid out, I'd like more information.
 
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Old 04-01-11, 09:41 PM
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Try loosening the gas cap when it dies and see if it will start back up. If so, replace the gas cap, or clear the cap vent out. If it still doesn't start, check for spark when it dies. If no spark, replace the coil.
 
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Old 04-01-11, 11:48 PM
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chuckalm

When it is running, it runs fine, in fact it usually takes me about 3 hours to cut my entire yard and it keeps running the whole time. If I stop and turn it off though, it will not start until it cools off for a while. It turns over normally until the battery goes down from cranking. Even jumping it willl not make a difference.
 
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Old 04-02-11, 08:20 PM
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Cheese; It does not die when running, in fact it runs quite well and I think it would run forever if I could keep gas in it. The problem is only when I turn it off when hot, then try to re-start before it has a chance to cool down. It just won't start. It will start hot occasionally if I keep trying long enough but usually the battery runs down, not because the battery is bad though, but from cranking too long.
 
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Old 04-03-11, 11:58 AM
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But does it have spark when it won't start?
 
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Old 04-04-11, 03:52 PM
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Not sure. I'll have to check that. Kind of hard alone. Put a brick or two on the seat to close that safety switch, tie the clutch down to kill that safety switch, jam a screwdriver in the plug wire, hold the screw driver close to a ground and crank it over. Should see a spark, Right?
 
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Old 04-04-11, 04:12 PM
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Originally Posted by chuckalm View Post
Not sure. I'll have to check that. Kind of hard alone. Put a brick or two on the seat to close that safety switch, tie the clutch down to kill that safety switch, jam a screwdriver in the plug wire, hold the screw driver close to a ground and crank it over. Should see a spark, Right?
Go get an inline spark tester, you will use it in the future, then you can set on the seat and see it fire. Have a good one. Geo
 
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Old 04-04-11, 05:22 PM
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With the parking brake engaged the seat switch should not need to be made in order to start/spark....
 
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Old 04-04-11, 08:48 PM
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Correct, just put the park brake on and forget the seat. Pull the plug out, connect it to the wire, make sure the plug is touching metal on the engine, and crank it while watching for spark at the plug tip.
 
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Old 04-11-11, 10:49 PM
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chuckalm

I finally got to run the mower, it actually rained in Texas. Anyway, after finishing the lawn, I turned it off and it wouldn't start when hot as usual. I pulled the right plug, connected the plug wire and grounded it. It DID have spark. Funny thing happened though, when I did that, it started up with one cylinder with the plug in and connected and the other with the plug out. Tried the same on the right cylinder and nothing. Then the battery went dead from cranking. Only cranked for a very short time though. Cheese, you also suggested loosening the gas cap. I'll try that next week.
 
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Old 04-14-11, 08:20 PM
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Well, if it started on the other side, it had spark even though you got nothing. Try the gas cap thing next. Does applying partial choke help keep it running a little longer?
 
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Old 04-14-11, 08:55 PM
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I'll try the gas cap thing next and a new fuel filter. I don't need to apply partial choke as it runs great when running. It just won't re-start when hot, choke open or closed makes no difference. One other thing that I noticed when pulling the plugs. The right plug was black, but not to the point that it was fouled, and the left plug was tan like it should be. Remember, the right plug is the one that I had out when it started. Of course it didn't run too good on one cylinder. Uleau made a this comment earlier "My 1st thought when I read your post was a clogged fuel line,,, or possibly restricted intake or exhaust,,, while any of those would produce the symptoms you've laid out, I'd like more information". So many possibilities.
 
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Old 04-15-11, 09:49 AM
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You might make sure that both cylinders are actually popping. With the engine running pull the left plug wire off and see if it dies. You should notice a drop in rpm when pulling one wire off, but it should run on the other cylinder.
If one cylinder is not popping, the right one in this case, and you have spark, it could be something like a rocker arm off of the pushrod...I've seen this happen and the engine still perform normally where the owner was unaware of any performance loss until it was corrected and compared to running on both cylinders.
 
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Old 04-15-11, 10:07 PM
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I forgot it doesn't die. What engine is this? I'm still thinking ignition problems.
 
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Old 05-09-11, 08:08 AM
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I have a craftsman 18 hp with kohler opposed engine doing the same thing. Its hard to start when cold but will run when starts, it has quit once while running. It will start right back after running as long as you start it right away, but if you let it sit a few min it will just crank away. Any suggestions on what the problem is??
 
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Old 05-09-11, 09:29 AM
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Have you checked for spark?
 
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Old 06-17-12, 10:55 AM
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I have the same problem with my 20 hp B&S lawnmower. Did you find out why it wouldn't start when hot?
 
  #20  
Old 06-17-12, 07:46 PM
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Have you checked the fuel solenoid?
 
  #21  
Old 07-25-12, 11:35 AM
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Sounds like your float may be stuck
 
  #22  
Old 07-25-12, 02:33 PM
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Cool

Check compression next time it shuts down. Also sounds like to me like it's vapor locking,,,,try to cool it down somehow. Good luck.
 
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Old 04-14-13, 04:08 PM
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My craftsman riding mower dies once it has been used about an hour

My craftsman riding mower dies once it has been used about an hour. It will not start until it has cooled off. (several hours) Then it starts fine and runs again for another hour. I have had numerous folks look at it, and cannot figure it out.

I see this seems to be a common problem. Has anyone found the answer??
 
  #24  
Old 04-14-13, 05:46 PM
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That depends greatly on what you have, and if you have spark or not when it won't start.
 
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