As a rule of thumb, it should be no more that 18" long. Length should be OK, but double check to make sure you have a good solid ground. Here are some pointers. Be sure it is at least the same guage as the power wire. Make absolute sure that you removed any paint on the surface that you grounded it to and use star washers for a good solid connection. Never use a seat bolt (or other threaded bolt) for your ground. Poor grounds can cause all kinds of nightmares, including what you are describing in this thread. Hope this helps. Good luck and let us know if you solve your problem.