About this time last year, I bought a 1991 Miata with a supercharged 1.6 running Megasquirt. Included with the sale was a race shop built 1.6 that needed assembly, a log manifold, and used Nissan T25. Two weeks ago the build of that engine was finished and it was installed in the car. Now that I am tuning the car for the different engine (larger injectors, etc) I've noticed that the fuel pump runs continuously when the key is on. I hadn't noticed it before because I had always just started it and let TunerStudio live tune the car as I drove.
So I took the computer out of the car, and it is a PlugNPlay unit for 90-93 Miatas from Stratified Auto. Tracing the wiring, the violet wire (connector 1C) for the Circuit Opening Relay is connected to the +12V pad along with the white/red wire (connector 1B) that is +12V switched. The car is using a GM-style IAT sensor that is directly wired into the computer, and there is no jumper in the AFM connector. There is also no jumper in the Diagnostics connector and the ST SIGN fuse was already removed.
Reading more about MS makes me believe that the violet wire should be connected to the FP (fuel pump?) pad. It's my understanding that circuit provides +12V for 2 seconds if there is no RPM input; with RPMs it provides continuous power. That way the fuel pump would only prime briefly instead of running continuously when the key is on, engine off. Can anyone confirm this?
Nothing connected to FP:
TLDR: Should the violet wire (1C - Circuit opening relay) on a 1991 Miata be connected to the Fuel Pump circuit in MS?