* The engine may not be getting enough fuel. When the seat safety switch is bypassed, the fuel pump may not be able to provide enough fuel to the engine to keep it running. This can cause the engine to stall or die.
* The ignition may be faulty. If the ignition is not working properly, it may not be able to provide the spark needed to start the engine or keep it running. This can cause the engine to stall or die.
* The electrical system may be faulty. If the electrical system is not working properly, it may not be able to provide the power needed to start the engine or keep it running. This can cause the engine to stall or die.
If your John Deere mower dies after engaging the blades seat safety switch is bypassed, it is important to have it diagnosed by a qualified mechanic to determine the cause of the problem.