2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.

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Art T.

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
I have a craftsman riding tractor model 917.289240. I replaced the magneto and the mower takes between 3-5 seconds to turn off. Prior to replacing it, the mower turned off immediately when the key was turned to the stop (off) position. it’s an OEM magneto from B&S, not a cheap aftermarket part from Amazon.

Today, while mowing, the mower remained on with the blades cutting when I got up from the seat. could it be a bad seat switch or a bad interlock switch?

Any help is very much appreciated. Thank you!
 
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ILENGINE

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
Sounds like the kill wire that connects to the magneto isn't connected or isn't working. Could be a faulty coil in the aspect that the ground tab doesn't work but have never seen one. More likely not connected or something wrong with grounding circuit that is supposed to kill the spark when you get off the seat The key switch and the safety system both kill spark. Without that working it will not shutoff, and that 3-5 second delay when shutting off is the fuel solenoid shutting off fuel to the engine but not killing the spark.

Try removing the blower housing and with the engine running take a screwdriver and connect it between the kill tab on the coil and the engine block. If it shuts off then the issue is with the mower wiring. If it continued to run then the new module is bad.
 
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hlw49

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
Not sure about lawn tractors but a lot of ZTR mowers have a time delay of about 3 seconds when you bounce off the seat to keep the engine from dying in this situtation.
 
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Art T.

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
ILENGINE said:
Sounds like the kill wire that connects to the magneto isn't connected or isn't working. Could be a faulty coil in the aspect that the ground tab doesn't work but have never seen one. More likely not connected or something wrong with grounding circuit that is supposed to kill the spark when you get off the seat The key switch and the safety system both kill spark. Without that working it will not shutoff, and that 3-5 second delay when shutting off is the fuel solenoid shutting off fuel to the engine but not killing the spark.

Try removing the blower housing and with the engine running take a screwdriver and connect it between the kill tab on the coil and the engine block. If it shuts off then the issue is with the mower wiring. If it continued to run then the new module is bad.
Click to expand...
Thanks for your help ILENGINE. Did exactly what you suggested. The kill wire was attached to the magneto. I removed it and the mower continued running after placing a screw driver between the kill tab and the engine block. Looks like this new OEM magneto is bad. So much for opting to buy from B&S instead of an after market on Amazon.
 
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Art T.

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
I know nothing about circuitry so please excuse my ignorance. If I am understanding you correctly, the magneto failure also affects the key switch and safety system? And this is the reason the engine continues to run with the blades engaged when I get off the seat?

Just trying to determine if the bad magneto is the root cause of these issues or if there is another problem as well.

Thank you for your help. I greatly appreciate it!
 
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ILENGINE

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
The fact that the kill tab on the magneto doesn't shut off the engine will also prevent the key from shutting off the engine and is only dying because the fuel afterfire solenoid on the carb is what is shutting off the engine, but will also prevent the safety system from shutting off the engine since it doesn't effect the fuel solenoid.
 
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Art T.

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
Thank you ILENGINE!! I appreciate the help.

I contacted B&S. They are sending me a new magneto. I’ll post again when I receive it and let you know the outcome.
 
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Art T.

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  • / 2 problems: Mower stays on when I get off the seat while blades are engaged; 3-5 second delay for mower to turn off.
Received the new magneto from B&S today. BINGO, problem solved! . Purposely bought an OEM from B&S instead of a cheap aftermarket off of Amazon but it crapped out after two days. B&S stood by their guarantee and replaced it. Just hope this one lasts longer than the last one.

Thanks for your help ILENGINE. You taught me a few things. Much appreciated!!
 
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