If your mechanical lift pump works (it should, it's new, right?), a leak between the LP and IP will be an external fuel leak, not an air intrusion leak. Conduct a fuel mist test (GP's removed, all injector lines tight). If all open cylinders don't mist fuel, install a length of clear tubing at the IP return outlet, loop it, and crank the engine. Any air going through the pump will absolutely collect in the loop. If you get air in the loop (after it's purged itself), you have a leak between the tank and lift pump. Pressurizing the fuel tank can be helpful finding it (no more than 5 PSI or so on an old tank).

Check Kennedy's site, and/or a local Stanadyne certified shop, IF it comes to the need of a replacement pump, costs should be similar, so also consider the customer service in the price. Run all the tests first, to verify a healthy or failed pump.

The "click" heard/felt at the IP when connecting/disconnecting the pink wire is the ESS (Engine Stop Solenoid, fuel solenoid, etc.). Clicking only indicates the solenoid is working. If fuel passes through the pump with it "on", and doesn't when it's "off", it's working just fine. If it doesn't work, it will either not allow any fuel and not start/run, or it won't close, and the engine will not stop when the key is off. Keep it that simple. If it's clicking, don't mess with it. The result can be a run-away engine (and a need of clean shorts).