Next task, fuel pump

 One thing I missed from my wiring update was that the fuel pump is being very quiet. Also the radiator fan is being very not-quiet! The fan I'm not bothered about, there will be some swapped voltage somewhere that is causing the relay to click and run the fan. But the fuel pump is a worry.

The fuel pump should run off the circuit opening relay, via a blue red wire (the other end is a black earth). The circuit opening relay connects blue red to light green, which comes from the airflow meter. Again, the other end of the air flow meter connection is black earth.

But that's not all. It looks like that when the light green is dropped to earth by the MAF, the white red into the circuit opening relay is fed on to the blue red. That's what makes the fuel pump run. 

So in theory if I ground the light green with the ignition on, the fuel pump should run. So that's one thing I can check.

According to this article https://www.miata.net/garage/fuelpumpdiag.html there's a few things to check on that route;

• Main relay clicking on when I turn on ignition. There is a click but it could be the fan relay rather than the main relay. Should be an easy check with a screwdriver to feel the click though.
• 12 volts to the fuel pump. Sounds simple enough, but I'll have to do it from the connector rather than the rear of the car as my arms aren't long enough. Apparently it should be 12 volts on crank and then for 3-5 seconds after.
• Add a jumper between fuel pump and ground pins on the diag connector. Since I don't have a diag connector this could be a challenge, however all it's doing in reality is grounding the light green wire which I can do as I have intimate knowledge of most of the wires on the car!
• This is where it gets a bit weird. It talks about 4 wires, with red blue going to the fuel pump and light green to the ECM. The other two should measure 12 volts DC, but by my reckoning that means white red from the main relay, and violet from the stop fuse. But where is the fifth wire, the black? Maybe it's not included? 
• The green wire should connect to ground when trying to start the engine, if not and it shows 5 volts when measuring voltage, then the ECM is toast. 
• Of course the last test is to apply voltage direct to the pump to hear it run, so that I can try as well. 

(Later that same day). So I didn't get much time in the garage (the new job is hard work and being tired in the garage never seems to be a safe combination), but I did check the main relay and it was clicking, but the injector relay wasn't. Opening the MAF flap didn't appear to wake things up either, so now I'm on to buzzing out wires and checking voltages. Just checking on Ebay a replacement ECM is around £70 (B63H is the search term apparently), so while I hope I've not blown anything up (not expecting it at this stage) it should be pretty easy to get a replacement. 

Oh, and I had a suspicion that in my dim and distant past I'd bought a spark plug tester, and just checking my toolbox I have indeed got one. So I'll also check spark while I'm here to see if that is ok.