FiTech EFI system

Here's a new one, for me at least. After running for a month or so, my unit stopped working today. Power adder 1200, fuel only. The engine fires, but then immediately dies. I noticed that I don't have any RPM reading. It stays at 0. My regular analog tach reads fine. All other readings; MAF, Temp, AFR, etc. appear to be reading fine on the handheld.

I tried re-writing my saved config profile and power cycling. That didn't work. So, I tried resetting the default v8 profile. Same thing. Engine starts briefly and then immediately dies with no change in the RPM. I've checked my blue tach wire, reseated all of the fuses and checked all of the connections at the TB and at my power sources.

Everything else is fine. Clean fuel, good fuel pressure. Spark is good, cranking power is great. It just starts and in less than a second just dies, like somebody pulled the coil wire and the RPM stays stuck at 0.