Are your readings the same on every channel or are your results parabolic? your antenna has the adjustable threaded tip, you need to adjust it so the reading on 1 & 40 are the same or similar and you need to put the tip back after you adjust it.
You def have an issue. run a temp ground wire directly to the bracket. do not try to transmit with your cb, listening is ok.
High swr on all channels is a significant indicator that you have a ground issue or other installation issue
You need to check channel 20 to make sure your getting a parabolic swr reading. if your getting the same swr reading across all the channels something else is wrong , i.e. pinched cable etc.
You can just run a temporary wire from the ground of the battery terminal to the mounting bracket bolt...
You can try running power & ground directly to the cb itself, also bring a ground wire to the antenna mount to see if that helps (just throw up a temp wire) also how tall is the antenna. it should be atleast 1' taller than the tallest object on your roof, rtt etc.
what's your swr reading at...