Fuel pump won't prime when I turn the key

So after getting my turbo Miata powered Spitfire running and driving, I had an issue with the fuel pump not priming. Turn key, nothing,  no clicks from the solenoid, just silence. I ended up replacing the fuel pump (was just an old used one I purchased to test with anyway) and ran some good grounds and it started working fine. So last week, driving it around to get some miles on it before going to the tuner's,  I had a oil leak from the oil return into the oil pan and had to pull the pan to fix the issue. So this involved removing the exhaust, pulling the intake lines, slave cylinder and motor mounts so I could lift the engine a little and pull the pan. Put it all back together and tried to start it up. Back to the fuel pump not priming. Any ideas? I had already tested the solenoid, fuses, swapped the main relay previously before I got it working by replacing the pump and making sure  I had a good ground. Not sure what would be causing this after the disassembly as it has worked perfectly for the last few weeks.......

Run a direct  wire to the pump to see if it runs.  If not check the ground.  If it runs with a direct wire then the switch could be the problem

Just a matter of systematic checking.

Agreed, but was just checking to see if anyone has experienced something similar. This car has a stripped down NB wiring harness, so it is basically a Miata electrically. I am 100% sure the pump will spin when I hit it with a direct wire as it is new, same with the pump solenoid, but can easily check both. I think one of engine sensors (crank or cam position) affects whether the fuel pump runs, so trying to figure out what I might have disturbed when I tore it all apart this weekend.

Stupid question but is it expecting to see a crank signal before the pump primes?  DSMs are that way - no prime with key until the crank angle sensor sees input.

I was thinking the same thing, the crank angle sensor is right next to what I was working on, so it could be the issue. I will check the gap tomorrow as it could have been moved and reseat the connector. I can also check if the Hydra is seeing the sensor.

When I had the same problem with my Nissan truck an auto electric shop found there was no ground from the ecu to the FP.  They ran a straight wire and it worked. 

So back out to the garage, looked at the crank position sensor, connections are tight and gap is correct. I turned the key a few time and nothing, then turned it and the fuel pump primed a few times. Now won't prime when I turn the key. Bad ignition switch? Switch is Triumph/Lucas, wired to the Miata wiring harness, worked for months with no issues. Or is this a bad main relay? I seem to remember you would hear the main relay click and the fuel pump prime when you switch on the key normally?

Sounds like a spotty connection somewhere that was never fixed but has come back.  

Check the pump - it will probably work. Check the solenoid. And I’d suggest you take it apart to check the connections as well as all of the grounds in the system.  

Well, I wiggled the main relay (JE16) and now it and the fuel pump are working, but not 100% of the time. So I don't trust it so I'll swap it out with a spare tonight. So either the relay or the connections are loose in my junction box.

Main relay fixed it, swapped with another one, sprayed the connectors first (look clean, but as a precaution), fired right up.