Lawn mower won't start with out being jump started . Changed battery. After jump starting mower and while mowing engine stalls while mower deck engaged . If mower deck is shut off before it looses complete power it will continue to run . but eventually it stalls out any way and will not restart with out jump starting.

SOURCE: lawnmower

There may be a thermal fuse fitted to the motor, sometimes they reset when they cool down. Sometimes they are a one shot fuse, when they blow the have to be replaced.
There may also be a reset switch on or inside the operating lever/switch.
Have you also checked the operating switch/lever for a bad connection or a wire come loose.

SOURCE: MTD Yard Machine, 3.5HP /

Hi,

Have you checked the primers on both of these units? It is possible that the primers are not putting enough fuel into the system. Look for holes or torn edges. Depending on the engine models. Also it can be lack of necessary vacuum and compression in the combustion chamber. But most probably it is a carb issue. It is suggested to rebuild the carburetor. Also when you clean the carburetor make sure the jet screws are seated in proper position in the way when you put the jets back in, you know to lightly seat them first and then turn them back out to their correct position before you started.

Please get back to us if you have further query else please accept the suggestion.
Thank you for contacting fixya.com

SOURCE: changed bag now motor won't start. The beater still works

you may have debris in the area around the motor, or it may have something lodged in the motor.