Why is my Cb working when i unplug the ground? Also, is there anyway to eliminate the noise of the engine in the radio?

 

You may have a radio that is designed for a negative ground , meaning it can get its ground through the mounting bracket or through the ground side of the coax cable.Do you have the owner's manual for it ? If it says pos or neg ground in the manual then there is a short in the radio.
The noise you're getting is most likely wideband rf from the fuel pump.The easiest way to tell is after the truck sits for a while , turn on the radio then turn the key to run .The fuel pump runs for a second or 2 and you'll hear it in the radio.

 

It IS negative ground and so is your vehicle. The (-) side of the CB's circuit board is grounded to the CB's chassis and the shield of the antenna. So in the absence of the power connector's ground, it can pick it up through the mounting bracket or the antenna cable.

 

The (-) side of the CB's circuit board is grounded to the CB's chassis and the shield of the antenna. So in the absence of the power connector's ground, it can pick it up through the mounting bracket or the antenna

Not always.Most all radios have the circuit board connected to the chassis ground through capacitors which do not pass DC.This is so the radio can be used in a positive ground vehicle such as some tractor trailors .I remember a guy hooking up an old Johnson cb in a Mack.He neglected to isolate the radio from touching the dash and it fried the power lead to the radio as he was going down the road.Filled the whole cab with smoke.

 

Very, very few radios without negative grounded circuit boards. You're unlikely to every see one.