stock tach not working properly
 

I installed a accel coil and my stock tach doesn't go over 3,000 RPM's. It worked with the stock coil. I am going to put the stock one back on and see if that solves the problem, but I was wondering if there is anything else I can do to get the tach to work again. I noticed there was a green wire hanging around the coil when I disconnected it. The only wires going into the connector are red and tan. Thanks for any suggestions.