Vehicle will not start with tachometer connected.
This is caused generally by 3 things:
1. The Tachometer is on the positive side of the coil or the coil is installed backwards. Check the the key on ignition lead is on the opposite side of the coil. A vehicle will run with the coil wired backwards
2. Tachometer signal wire is grounded along the wire path. This will ground out the coil allowing the spark not to fire. Disconnect the signal wire at the gauge, re-start the vehicle. If the vehicle does not start the signal wire is shorting to ground.
3. Ballast resistor is bad. Adding the small tach load can often have a ballast resistor that is on the edge of going bad prevent the vehicle from starting. Check ballast resistor according to you vehicle repair manual.
If this does not work please contact NVU tech line at 248-850-5482 and have code ACT7 available