I am looking to get an air rifle for pest control up to the size of foxes or coyotes. I like the idea of a pcp but I don’t have it in the budget to get a big tank or a compressor so I would have to a hand pump. I would need the gun ready for when I needed it, can you leave a pcp charged for an extended period time or would it damage it?
There are no spring guns IMO that can ethically be thought to be useful on a coyote. I have taken coyotes with my .25 M-Rod set to near maximum power, .25, 34 grain pellet at 960 fps which is around 70 fpe and far more than any spring gun can generate.
You would be better off to get a good .22 rifle, a properly acquired, tax stamp legal .22 PB suppressor and some CCI Suppressor or Subsonic HP or Segmented rounds and even then coyotes can be tough, heck, even raccoons can be tougher, the big one can put up a fuss.