Getting out, but not recieving well...

Question

I drive a truck for a living, Ive always had a good cb. Recently I just switched trucks that already had 2 antennas set up with all the coax run in it. I put in my cb and I am not recieving any thing farther than a half mile, however I can send for at least 2 or three miles or better. Not sure what to do short of ripping out the coax and putting on new antennas. Any suggestions?