Another Electric Fuel pump wiring question.
A 30 amp breaker for an electric fuel pump... wow!!!
Put a 10-15 amp fuse in the line from battery/alternator to relay and go with it. 10 ga wire... good god what's that pump pull for amps? Most pumps don't pull over 8 amps unless they are HUGE. 12 Ga wire is usually sufficient if the run is short from battery/alternator to pump.
I put the pressure cut off in the ignition circuit with a bypass switch when starting the car. You want to protect the engine from low oil pressure, that's how I do it. No oil pressure, no ignition!
Too bad that kit likely has a chinese relay in it. Check every single connector for proper crimping. They are bad for not being terminated correctly.