Craftsman 15" lawn tractor

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  #1  
Old 05-31-05, 09:24 PM
amarc
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Craftsman 15" lawn tractor

I have a Craftzman Model No 944.605350 Lawn Tractor with a B&S 28N707 15HP engine and it has a couple of problems. First when it is cold it has a hard time starting with some backfires, but eventualy it will start. Once it has started it will idle and run fine. When you shut off the ignition it will backfire a couple of times before it comes to a stop. So far I have taken the carb off and cleaned it and everything seems to be moving freely including the anti backfire solenoid. If you start the engine when it is still hot or while it is still worm then it will start start at the first try but still with the odd backfire in the beginning and again after you turn the ignition off. Any advice will be greatly appreciated.

Alex
 
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Old 05-31-05, 11:44 PM
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Hello Alex,

Look at the position of the spark plug wire. I've seen this on these ohv engines, and the plug wire is too close to the exhaust on a lot of them. It sometimes lays on the exhaust pipe and melts through enough to cause ignition problems and backfiring. If it's melted, best shot would be to replace the coil and route the plug wire away from the exhaust the best you can.
 
  #3  
Old 06-05-05, 08:24 PM
amarc
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Sears riding mower update

Hi Chesse
Thanks for the reply. I checked the high voltage cable & it is free & clear. I don't think that is the problem. This mower belongs to an elderly neighbour and since he knows that I do all my own maintenance around the house he has asked me if I can help. This weekend I have spent a couple of hours on the mower & this is what I have determined so far.
1. If the mower has been standing for a day and you try to start it it would take a lot of trying before it will eventualy start. I have determined that the cylinder gets flooded with gas and untill you get rid of that gas it will not start. If you remove the spark plug after a couple of tries you will see that the spark plug is all wet and if you dry it with air and reinstall it, the engine would start on the first try. From then on if you turn the ignition off and then you try starting again it will fire every time with no problem. (why it is doing this only when it has be standing for a day has me baffled). I have checked the oil and there appears not do have any gas mixed with it. I have removed the carbourator, cleaned it and everything on it is moviing freely. I measured the compression and it measures 100PSI which seems good to me. When I check the spark it looks good. If you remove the spark plug before starting a cold engine it is dry so the gas must get there as you try to start it.
2 The second problem is actually the problem that concerns me more. Soon after the motor fires and it is starting to speed up to idle you can hear three or four hard kncks before it comes to idle. After this it will run fairly smooth untill you turn the ignition off and then again you hear a few hard knocks befor it comes to a complete stop.
I have fixed a few lawn mowers with a smaller engine so I am not very familiar what to expect with a biger engine and if the knocking is still there when it is running and is being hidden.
Do you think the two problems are related? Do you think something in the carbourator is causing the flooding and the knocking? Could it be a worn rod bearing?
Any suggestions as to what I can try next would be appreciated.
Sorry for the long reply.
Thanks
Alex
 
  #4  
Old 06-06-05, 11:17 PM
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The flooding would be a carb related problem. You'll probably have to replace the needle.

The hard knocking you hear is caused by loose engine mounting bolts. Tighten them and you should be fine.
 
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