Autogauge Tach

I've been having starting problems with my car recently. It will start fine most of the time but once in a while it will refuse to start. It turns over but there's no spark. Wait 5 minutes and then it will start. I'm using an FBO ignition that is about 6 years old and have had no problems with it till now.
I did add an Autogauge tach that I bought new from Summit in August. Saturday I tried to start it and it wouldn't fire, so I took off the tach signal wire from the coil and it started right up. Look's like the tach is the culprit and now I have to try and send it back.
Should I get the same kind to replace it or try something else? The tach worked fine except for starting problem. Anyone have issues with Autogauge brand products?