I had the same problem a couple of weeks ago we hooked up the MSD & it wouldn`t spark, I checked everything 3-4 times but no spark , I then replaced the MSD with a Digital Holley Annihilator system, & it fired up right away , meanwhile I had the MSD tested & it is supposed to be good but I have not bothered to hook it up & try it again , the Holley is better anyway as it is digital not analog & has a built in rev limiter that doesn`t require $50 worth of Chips to set it