97 jetta 2.0 want start ignition problems

i have a 97 jetta 2.0 that want fire i have put i new hall sensor and new coil on it and it still fire i have tired to test volts from the disbutor wires and it has 12 volts on the outer two also i have put a test light on the center wire coming out of the coil and it flashs when turning over the engines the only way that i can get it to fire is to put the test light on the ground wire and turn the key on and put the test light to the the red and black wire going into the coil also it will fire when i turn the keys off and on thanks any help would be appriated