We actually install a default health check when you remove them, so removing it probably didn’t do what you were expecting.
If you run fly vm status c7ca037a you can see a bit more detail about why it stopped. It seems like the health check might be the problem.
Try adding this to the health check block in the config. This will give the VM more time to come up before it’s deemed unhealthy:
grace_period = "10s"