One other thing I forgot to mention it probably sounds stupid but make sure you have the correct wire out of the EMS connected to the Tacho and that it is programmed properley in the ems.
This can be checked with a 12V test light but it must be between 12V and the tach wire NOT ground and the wire.

Cheers

Awesome, thanks guys! I'll give it a whirl this weekend and let you know how I get on.

Scotty,
The stinger EMS has what is called "Open Collector" outputs, this is a way you can use pairs of transistors to switch things on and off. The key in getting it all to work properley is that the device you are switching "ie. Your Tach Pulse" must be connected between 12V and the switch wire on the EMS.
Most guage manfacturers use a high impedance input so as not to load any normal ignition system when connected. This is what I feel will be causing your probs as it doesn't provide an acceptable collector load for the transistor array inside the EMS.
Similar to the EMS solution I have had sucess in the past by using a higher value resistor about 10K ohm between 12V and the Tach pulse output on the EMS, this resistor becomes the load and allows the transistor to switch.
If this doesn't work I can build an OP Amp or PIC based device to do the job but the resistor has worked for me many times.
Let me know

I dont know how to fix but by using an electronic ignition unit in your car will provide you with another tacho cable which might work for your problem...

outgoing wires from the elec ignition is
-coil negative
-points positive
-ground
-12v input
-tachometer

they take approx 4-6 hours to make 1st time. with practice you can make them much faster. my last was 2 hrs and ive only made 3 of em.

search www.jaycar.com.au for "Universal High Energy Ignition Kit". its $52.95 AU.

Hi all,
I have an 5" Autometer Autogauage in my ute, which has a stinger ems in it.

The tacho signal needs to be a 12v square wave signal (as per the autometer website) and the people from EMS have suggested that in order to make their signal sufficient I should splice into the tacho wire a 12v connection seperated by a 500 - 1000 ohm resistor.

The problem is, initially the shift light was self testing when I turned the car on, and now that I have tried this setup, it no longer self tests. And the suggested setup did not work. ie: the tacho did not work.

Any ideas? (aside from buying an adapter from Autometer which creates the signal from the coils)

Thanks peoples