Paxtoned 416 won t fire with lid on when engine is cool

I think you are getting fuel perk/ siphon when sitting. Or else NO fuel in the morning.

Is the fuel tank for certain vented? If the carbon can/ evap system has been removed/ changed, the vent system is suspect.

What are you running for a pump, electric or mechanical? If it's not electric, try to determine if the fuel is pulling back over night. Pull the lid before cranking, pump the throttle, and see if you have fuel immediately from the accel pump